Palindrome Partitioning | DP-17
Given a string, a partitioning of the string is a palindrome partitioning if every substring of the partition is a palindrome. For example, “aba|b|bbabb|a|b|aba” is a palindrome partitioning of “ababbbabbababa”. Determine the fewest cuts needed for a palindrome partitioning of a given string. For example, minimum of 3 cuts are needed for “ababbbabbababa”. The three cuts are “a|babbbab|b|ababa”. If a string is a palindrome, then minimum 0 cuts are needed. If a string of length n containing all different characters, then minimum n-1 cuts are needed.
Examples :
Input : str = “geek”
Output : 2
We need to make minimum 2 cuts, i.e., “g ee k”
Input : str = “aaaa”
Output : 0
The string is already a palindrome.
Input : str = “abcde”
Output : 4
Input : str = “abbac”
Output : 1
This problem is a variation of Matrix Chain Multiplication problem. If the string is a palindrome, then we simply return 0. Else, like the Matrix Chain Multiplication problem, we try making cuts at all possible places, recursively calculate the cost for each cut and return the minimum value.
Let the given string be str and minPalPartion() be the function that returns the fewest cuts needed for palindrome partitioning. following is the optimal substructure property.
Using Recursion
// i is the starting index and j is the ending index. i must be passed as 0 and j as n-1
minPalPartion(str, i, j) = 0 if i == j. // When string is of length 1.
minPalPartion(str, i, j) = 0 if str[i..j] is palindrome.
// If none of the above conditions is true, then minPalPartion(str, i, j) can be
// calculated recursively using the following formula.
minPalPartion(str, i, j) = Min { minPalPartion(str, i, k) + 1 +
minPalPartion(str, k+1, j) }
where k varies from i to j-1C++
// C++ Code for Palindrome Partitioning// Problem#include <bits/stdc++.h>using namespace std;bool isPalindrome(string String, int i, int j){ while(i < j) { if(String[i] != String[j]) return false; i++; j--; } return true;}int minPalPartion(string String, int i, int j){ if( i >= j || isPalindrome(String, i, j) ) return 0; int ans = INT_MAX, count; for(int k = i; k < j; k++) { count = minPalPartion(String, i, k) + minPalPartion(String, k + 1, j) + 1; ans = min(ans, count); } return ans;}// Driver codeint main() { string str = "ababbbabbababa"; cout << "Min cuts needed for " << "Palindrome Partitioning is " << minPalPartion(str, 0, str.length() - 1) << endl; return 0;}// This code is contributed by rag2127 |
Java
// Java Code for Palindrome Partitioning// Problempublic class GFG{ static boolean isPalindrome(String string, int i, int j) { while(i < j) { if(string.charAt(i) != string.charAt(j)) return false; i++; j--; } return true; } static int minPalPartion(String string, int i, int j) { if( i >= j || isPalindrome(string, i, j) ) return 0; int ans = Integer.MAX_VALUE, count; for(int k = i; k < j; k++) { count = minPalPartion(string, i, k) + minPalPartion(string, k + 1, j) + 1; ans = Math.min(ans, count); } return ans; } // Driver code public static void main(String args[]) { String str = "ababbbabbababa"; System.out.println("Min cuts needed for " + "Palindrome Partitioning is " + minPalPartion(str, 0, str.length() - 1)); }}// This code is contributed by adityapande88. |
Python3
# Python code for implementation of Naive Recursive# approachdef isPalindrome(x): return x == x[::-1]def minPalPartion(string, i, j): if i >= j or isPalindrome(string[i:j + 1]): return 0 ans = float('inf') for k in range(i, j): count = ( 1 + minPalPartion(string, i, k) + minPalPartion(string, k + 1, j) ) ans = min(ans, count) return ansdef main(): string = "ababbbabbababa" print( "Min cuts needed for Palindrome Partitioning is ", minPalPartion(string, 0, len(string) - 1), )if __name__ == "__main__": main()# This code is contributed by itsvinayak |
C#
// C# Code for Palindrome Partitioning// Problemusing System;public class GFG{ static bool isPalindrome(string String, int i, int j) { while(i < j) { if(String[i] != String[j]) return false; i++; j--; } return true; } static int minPalPartion(string String, int i, int j) { if( i >= j || isPalindrome(String, i, j) ) return 0; int ans = Int32.MaxValue, count; for(int k = i; k < j; k++) { count = minPalPartion(String, i, k) + minPalPartion(String, k + 1, j) + 1; ans = Math.Min(ans, count); } return ans; } // Driver code static public void Main (){ string str = "ababbbabbababa"; Console.WriteLine("Min cuts needed for "+ "Palindrome Partitioning is " + minPalPartion(str, 0, str.Length - 1)); }}// This code is contributed by avanitrachhadiya2155 |
Javascript
<script>// Javascript code for Palindrome// Partitioning Problemfunction isPalindrome(String, i, j){ while (i < j) { if (String[i] != String[j]) return false; i++; j--; } return true;}function minPalPartion(String, i, j){ if (i >= j || isPalindrome(String, i, j)) return 0; let ans = Number.MAX_VALUE, count; for(let k = i; k < j; k++) { count = minPalPartion(String, i, k) + minPalPartion(String, k + 1, j) + 1; ans = Math.min(ans, count); } return ans;}// Driver codelet str = "ababbbabbababa";document.write("Min cuts needed for " + "Palindrome Partitioning is " + minPalPartion(str, 0, str.length - 1)); // This code is contributed by suresh07</script> |
Output:
Min cuts needed for Palindrome Partitioning is 3
Time Complexity: O(2n)
Auxiliary Space: O(n)
Using Dynamic Programming :
Following is Dynamic Programming solution. It stores the solutions to subproblems in two arrays P[][] and C[][], and reuses the calculated values.
C++
// Dynamic Programming Solution for// Palindrome Partitioning Problem#include <bits/stdc++.h>using namespace std;// Returns the minimum number of cuts// needed to partition a string// such that every part is a palindromeint minPalPartion(string str){ // Get the length of the string int n = str.length(); /* Create two arrays to build the solution in bottom up manner C[i][j] = Minimum number of cuts needed for palindrome partitioning of substring str[i..j] P[i][j] = true if substring str[i..j] is palindrome, else false Note that C[i][j] is 0 if P[i][j] is true */ int C[n][n]; bool P[n][n]; // Every substring of length 1 is a palindrome for (int i = 0; i < n; i++) { P[i][i] = true; C[i][i] = 0; } /* L is substring length. Build the solution in bottom up manner by considering all substrings of length starting from 2 to n. The loop structure is same as Matrix Chain Multiplication problem ( See https:// www.geeksforgeeks.org/matrix-chain-multiplication-dp-8/ )*/ for (int L = 2; L <= n; L++) { // For substring of length L, set // different possible starting indexes for (int i = 0; i < n - L + 1; i++) { int j = i + L - 1; // Set ending index // If L is 2, then we just need to // compare two characters. Else // need to check two corner characters // and value of P[i+1][j-1] if (L == 2) P[i][j] = (str[i] == str[j]); else P[i][j] = (str[i] == str[j]) && P[i + 1][j - 1]; // IF str[i..j] is palindrome, then C[i][j] is 0 if (P[i][j] == true) C[i][j] = 0; else { // Make a cut at every possible // location starting from i to j, // and get the minimum cost cut. C[i][j] = INT_MAX; for (int k = i; k <= j - 1; k++) C[i][j] = min(C[i][j], C[i][k] + C[k + 1][j] + 1); } } } // Return the min cut value for // complete string. i.e., str[0..n-1] return C[0][n - 1];}// Driver codeint main(){ string str = "ababbbabbababa"; cout << "Min cuts needed for Palindrome" " Partitioning is " << minPalPartion(str); return 0;}// This code is contributed by rathbhupendra |
C
// Dynamic Programming Solution for Palindrome Partitioning Problem#include <limits.h>#include <stdio.h>#include <string.h>// A utility function to get minimum of two integersint min(int a, int b) { return (a < b) ? a : b; }// Returns the minimum number of cuts needed to partition a string// such that every part is a palindromeint minPalPartion(char* str){ // Get the length of the string int n = strlen(str); /* Create two arrays to build the solution in bottom up manner C[i][j] = Minimum number of cuts needed for palindrome partitioning of substring str[i..j] P[i][j] = true if substring str[i..j] is palindrome, else false Note that C[i][j] is 0 if P[i][j] is true */ int C[n][n]; bool P[n][n]; int i, j, k, L; // different looping variables // Every substring of length 1 is a palindrome for (i = 0; i < n; i++) { P[i][i] = true; C[i][i] = 0; } /* L is substring length. Build the solution in bottom up manner by considering all substrings of length starting from 2 to n. The loop structure is same as Matrix Chain Multiplication problem ( See https:// www.geeksforgeeks.org/matrix-chain-multiplication-dp-8/ )*/ for (L = 2; L <= n; L++) { // For substring of length L, set different possible starting indexes for (i = 0; i < n - L + 1; i++) { j = i + L - 1; // Set ending index // If L is 2, then we just need to compare two characters. Else // need to check two corner characters and value of P[i+1][j-1] if (L == 2) P[i][j] = (str[i] == str[j]); else P[i][j] = (str[i] == str[j]) && P[i + 1][j - 1]; // IF str[i..j] is palindrome, then C[i][j] is 0 if (P[i][j] == true) C[i][j] = 0; else { // Make a cut at every possible location starting from i to j, // and get the minimum cost cut. C[i][j] = INT_MAX; for (k = i; k <= j - 1; k++) C[i][j] = min(C[i][j], C[i][k] + C[k + 1][j] + 1); } } } // Return the min cut value for complete string. i.e., str[0..n-1] return C[0][n - 1];}// Driver program to test above functionint main(){ char str[] = "ababbbabbababa"; printf("Min cuts needed for Palindrome Partitioning is %d", minPalPartion(str)); return 0;} |
Java
// Java Code for Palindrome Partitioning// Problempublic class GFG { // Returns the minimum number of cuts needed // to partition a string such that every // part is a palindrome static int minPalPartion(String str) { // Get the length of the string int n = str.length(); /* Create two arrays to build the solution in bottom up manner C[i][j] = Minimum number of cuts needed for palindrome partitioning of substring str[i..j] P[i][j] = true if substring str[i..j] is palindrome, else false Note that C[i][j] is 0 if P[i][j] is true */ int[][] C = new int[n][n]; boolean[][] P = new boolean[n][n]; int i, j, k, L; // different looping variables // Every substring of length 1 is a palindrome for (i = 0; i < n; i++) { P[i][i] = true; C[i][i] = 0; } /* L is substring length. Build the solution in bottom up manner by considering all substrings of length starting from 2 to n. The loop structure is same as Matrix Chain Multiplication problem ( See https:// www.geeksforgeeks.org/matrix-chain-multiplication-dp-8/ )*/ for (L = 2; L <= n; L++) { // For substring of length L, set different // possible starting indexes for (i = 0; i < n - L + 1; i++) { j = i + L - 1; // Set ending index // If L is 2, then we just need to // compare two characters. Else need to // check two corner characters and value // of P[i+1][j-1] if (L == 2) P[i][j] = (str.charAt(i) == str.charAt(j)); else P[i][j] = (str.charAt(i) == str.charAt(j)) && P[i + 1][j - 1]; // IF str[i..j] is palindrome, then // C[i][j] is 0 if (P[i][j] == true) C[i][j] = 0; else { // Make a cut at every possible // localtion starting from i to j, // and get the minimum cost cut. C[i][j] = Integer.MAX_VALUE; for (k = i; k <= j - 1; k++) C[i][j] = Integer.min(C[i][j], C[i][k] + C[k + 1][j] + 1); } } } // Return the min cut value for complete // string. i.e., str[0..n-1] return C[0][n - 1]; } // Driver program to test above function public static void main(String args[]) { String str = "ababbbabbababa"; System.out.println("Min cuts needed for " + "Palindrome Partitioning is " + minPalPartion(str)); }}// This code is contributed by Sumit Ghosh |
Python3
# Dynamic Programming Solution for# Palindrome Partitioning Problem# Returns the minimum number of# cuts needed to partition a string# such that every part is a palindromedef minPalPartion(str): # Get the length of the string n = len(str) # Create two arrays to build the # solution in bottom up manner # C[i][j] = Minimum number of cuts # needed for palindrome # partitioning of substring str[i..j] # P[i][j] = true if substring str[i..j] # is palindrome, else false. Note that # C[i][j] is 0 if P[i][j] is true C = [[0 for i in range(n)] for i in range(n)] P = [[False for i in range(n)] for i in range(n)] # different looping variables j = 0 k = 0 L = 0 # Every substring of length # 1 is a palindrome for i in range(n): P[i][i] = True; C[i][i] = 0; # L is substring length. Build the # solution in bottom-up manner by # considering all substrings of # length starting from 2 to n. # The loop structure is the same as # Matrix Chain Multiplication problem # (See https://www.geeksforgeeks.org / matrix-chain-multiplication-dp-8/ ) for L in range(2, n + 1): # For substring of length L, set # different possible starting indexes for i in range(n - L + 1): j = i + L - 1 # Set ending index # If L is 2, then we just need to # compare two characters. Else # need to check two corner characters # and value of P[i + 1][j-1] if L == 2: P[i][j] = (str[i] == str[j]) else: P[i][j] = ((str[i] == str[j]) and P[i + 1][j - 1]) # IF str[i..j] is palindrome, # then C[i][j] is 0 if P[i][j] == True: C[i][j] = 0 else: # Make a cut at every possible # location starting from i to j, # and get the minimum cost cut. C[i][j] = 100000000 for k in range(i, j): C[i][j] = min (C[i][j], C[i][k] + C[k + 1][j] + 1) # Return the min cut value for # complete string. i.e., str[0..n-1] return C[0][n - 1]# Driver codestr = "ababbbabbababa"print ('Min cuts needed for Palindrome Partitioning is', minPalPartion(str)) # This code is contributed# by Sahil shelangia |
C#
// C# Code for Palindrome Partitioning// Problemusing System;class GFG { // Returns the minimum number of cuts needed // to partition a string such that every // part is a palindrome static int minPalPartion(String str) { // Get the length of the string int n = str.Length; /* Create two arrays to build the solution in bottom up manner C[i][j] = Minimum number of cuts needed for palindrome partitioning of substring str[i..j] P[i][j] = true if substring str[i..j] is palindrome, else false Note that C[i][j] is 0 if P[i][j] is true */ int[, ] C = new int[n, n]; bool[, ] P = new bool[n, n]; int i, j, k, L; // different looping variables // Every substring of length 1 is a palindrome for (i = 0; i < n; i++) { P[i, i] = true; C[i, i] = 0; } /* L is substring length. Build the solution in bottom up manner by considering all substrings of length starting from 2 to n. The loop structure is same as Matrix Chain Multiplication problem ( See https:// www.geeksforgeeks.org/matrix-chain-multiplication-dp-8/ )*/ for (L = 2; L <= n; L++) { // For substring of length L, set different // possible starting indexes for (i = 0; i < n - L + 1; i++) { j = i + L - 1; // Set ending index // If L is 2, then we just need to // compare two characters. Else need to // check two corner characters and value // of P[i+1][j-1] if (L == 2) P[i, j] = (str[i] == str[j]); else P[i, j] = (str[i] == str[j]) && P[i + 1, j - 1]; // IF str[i..j] is palindrome, then // C[i][j] is 0 if (P[i, j] == true) C[i, j] = 0; else { // Make a cut at every possible // location starting from i to j, // and get the minimum cost cut. C[i, j] = int.MaxValue; for (k = i; k <= j - 1; k++) C[i, j] = Math.Min(C[i, j], C[i, k] + C[k + 1, j] + 1); } } } // Return the min cut value for complete // string. i.e., str[0..n-1] return C[0, n - 1]; } // Driver program public static void Main() { String str = "ababbbabbababa"; Console.Write("Min cuts needed for " + "Palindrome Partitioning is " + minPalPartion(str)); }}// This code is contributed by Sam007 |
PHP
<?php// Dynamic Programming Solution for Palindrome Partitioning Problem // Returns the minimum number of cuts needed to partition a string// such that every part is a palindromefunction minPalPartion($str){ // Get the length of the string $n = strlen($str); /* Create two arrays to build the solution in bottom up manner C[i][j] = Minimum number of cuts needed for palindrome partitioning of substring str[i..j] P[i][j] = true if substring str[i..j] is palindrome, else false Note that C[i][j] is 0 if P[i][j] is true */ $C = array_fill(0, $n, array_fill(0, $n, NULL)); $P = array_fill(false, $n, array_fill(false, $n, NULL)); // Every substring of length 1 is a palindrome for ($i=0; $i<$n; $i++) { $P[$i][$i] = true; $C[$i][$i] = 0; } /* L is substring length. Build the solution in a bottom-up manner by considering all substrings of length starting from 2 to n. The loop structure is same as Matrix Chain Multiplication problem ( for ($L=2; $L<=$n; $L++) { // For substring of length L, set different possible starting indexes for ($i=0; $i<$n-$L+1; $i++) { $j = $i+$L-1; // Set ending index // If L is 2, then we just need to compare two characters. Else // need to check two corner characters and value of P[i+1][j-1] if ($L == 2) $P[$i][$j] = ($str[$i] == $str[$j]); else $P[$i][$j] = ($str[$i] == $str[$j]) && $P[$i+1][$j-1]; // IF str[i..j] is palindrome, then C[i][j] is 0 if ($P[$i][$j] == true) $C[$i][$j] = 0; else { // Make a cut at every possible location starting from i to j, // and get the minimum cost cut. $C[$i][$j] = PHP_INT_MAX; for ($k=$i; $k<=$j-1; $k++) $C[$i][$j] = min ($C[$i][$j], $C[$i][$k] + $C[$k+1][$j]+1); } } } // Return the min cut value for complete string. i.e., str[0..n-1] return $C[0][$n-1];} // Driver program to test the above function$str = "ababbbabbababa";echo "Min cuts needed for Palindrome Partitioning is " .minPalPartion($str);return 0;?> |
Javascript
<script>// javascript Code for Palindrome Partitioning// Problem // Returns the minimum number of cuts needed // to partition a string such that every // part is a palindrome function minPalPartion( str) { // Get the length of the string var n = str.length; /* * Create two arrays to build the solution in bottom up manner C[i][j] = Minimum * number of cuts needed for palindrome partitioning of substring str[i..j] * P[i][j] = true if substring str[i..j] is palindrome, else false Note that * C[i][j] is 0 if P[i][j] is true */ var C = Array(n).fill().map(()=>Array(n).fill(0)); var P = Array(n).fill().map(()=>Array(n).fill(false)); var i, j, k, L; // different looping variables // Every substring of length 1 is a palindrome for (i = 0; i < n; i++) { P[i][i] = true; C[i][i] = 0; } /* * L is substring length. Build the solution in bottom up manner by considering * all substrings of length starting from 2 to n. The loop structure is same as * Matrix Chain Multiplication problem ( See https:// * www.geeksforgeeks.org/matrix-chain-multiplication-dp-8/ ) */ for (L = 2; L <= n; L++) { // For substring of length L, set different // possible starting indexes for (i = 0; i < n - L + 1; i++) { j = i + L - 1; // Set ending index // If L is 2, then we just need to // compare two characters. Else need to // check two corner characters and value // of P[i+1][j-1] if (L == 2) P[i][j] = (str.charAt(i) == str.charAt(j)); else P[i][j] = (str.charAt(i) == str.charAt(j)) && P[i + 1][j - 1]; // IF str[i..j] is palindrome, then // C[i][j] is 0 if (P[i][j] == true) C[i][j] = 0; else { // Make a cut at every possible // localtion starting from i to j, // and get the minimum cost cut. C[i][j] = Number.MAX_VALUE; for (k = i; k <= j - 1; k++) C[i][j] = Math.min(C[i][j], C[i][k] + C[k + 1][j] + 1); } } } // Return the min cut value for complete // string. i.e., str[0..n-1] return C[0][n - 1]; } // Driver program to test above function var str = "ababbbabbababa"; document.write("Min cuts needed for " + "Palindrome Partitioning is " + minPalPartion(str));// This code is contributed by Rajput-Ji</script> |
Output:
Min cuts needed for Palindrome Partitioning is 3
Time Complexity: O(n3)
Auxiliary Space: O(n2)
We can optimize the above code a bit further. Instead of calculating C[i] separately in O(n^2), we can do it with the P[i] itself. Below is the highly optimized code of this problem:
C++
#include <bits/stdc++.h>using namespace std;int minCut(string a){ int cut[a.length()]; bool palindrome[a.length()][a.length()]; memset(palindrome, false, sizeof(palindrome)); for (int i = 0; i < a.length(); i++) { int minCut = i; for (int j = 0; j <= i; j++) { if (a[i] == a[j] && (i - j < 2 || palindrome[j + 1][i - 1])) { palindrome[j][i] = true; minCut = min(minCut, j == 0 ? 0 : (cut[j - 1] + 1)); } } cut[i] = minCut; } return cut[a.length() - 1];}// Driver codeint main(){ cout << minCut("aab") << endl; cout << minCut("aabababaxx") << endl; return 0;}// This code is contributed by divyesh072019. |
Java
import java.io.*;class GFG { public static int minCut(String a) { int[] cut = new int[a.length()]; boolean[][] palindrome = new boolean[a.length()][a.length()]; for (int i = 0; i < a.length(); i++) { int minCut = i; for (int j = 0; j <= i; j++) { if (a.charAt(i) == a.charAt(j) && (i - j < 2 || palindrome[j + 1][i - 1])) { palindrome[j][i] = true; minCut = Math.min(minCut, j == 0 ? 0 : (cut[j - 1] + 1)); } } cut[i] = minCut; } return cut[a.length() - 1]; } public static void main(String[] args) { System.out.println(minCut("aab")); System.out.println(minCut("aabababaxx")); }} |
Python3
def minCut(a): cut = [0 for i in range(len(a))] palindrome = [[False for i in range(len(a))] for j in range(len(a))] for i in range(len(a)): minCut = i; for j in range(i + 1): if (a[i] == a[j] and (i - j < 2 or palindrome[j + 1][i - 1])): palindrome[j][i] = True; minCut = min(minCut,0 if j == 0 else (cut[j - 1] + 1)); cut[i] = minCut; return cut[len(a) - 1];# Driver codeif __name__=='__main__': print(minCut("aab")) print(minCut("aabababaxx")) # This code is contributed by rutvik_56 |
C#
using System;using System.Collections.Generic; class GFG{ static int minCut(string a) { int[] cut = new int[a.Length]; bool[,] palindrome = new bool[a.Length, a.Length]; for (int i = 0; i < a.Length; i++) { int minCut = i; for (int j = 0; j <= i; j++) { if (a[i] == a[j] && (i - j < 2 || palindrome[j + 1, i - 1])) { palindrome[j, i] = true; minCut = Math.Min(minCut, j == 0 ? 0 : (cut[j - 1] + 1)); } } cut[i] = minCut; } return cut[a.Length - 1]; } // Driver code static void Main() { Console.WriteLine(minCut("aab")); Console.WriteLine(minCut("aabababaxx")); }}// This code is contributed by divyeshrabadiya07. |
Javascript
<script>function minCut(a) { var cut = new Array(a.length); var palindrome = new Array(a.length); for (var i = 0; i < a.length; i++) { var minCut = i; for (var j = 0; j <= i; j++) { if (a.charAt(i) == a.charAt(j) && (i - j < 5 || palindrome[j + 1][i - 1])) { palindrome[j,i] = true; minCut = Math.min(minCut, j == 0 ? 0 : (cut[j - 1] + 1)); } } cut[i] = minCut; } return cut[a.length - 1]; } document.write(minCut("aab")+"<br>"); document.write(minCut("aabababaxx"));// This code is contributed by shivanisinghss2110</script> |
Time Complexity: O(n2)
Auxiliary Space: O(n2)
An optimization to above approach
In the above approach, we can calculate the minimum cut while finding all palindromic substring. If we find all palindromic substring 1st and then we calculate minimum cut, time complexity will reduce to O(n2).
Thanks for Vivek for suggesting this optimization.
C++
// Dynamic Programming Solution for Palindrome Partitioning Problem#include <iostream>#include <bits/stdc++.h>#include <string.h>using namespace std;// A utility function to get minimum of two integersint min(int a, int b) { return (a < b) ? a : b; }// Returns the minimum number of cuts needed to partition a string// such that every part is a palindromeint minPalPartion(char* str){ // Get the length of the string int n = strlen(str); /* Create two arrays to build the solution in bottom-up manner C[i] = Minimum number of cuts needed for a palindrome partitioning of substring str[0..i] P[i][j] = true if substring str[i..j] is palindrome, else false Note that C[i] is 0 if P[0][i] is true */ int C[n]; bool P[n][n]; int i, j, k, L; // different looping variables // Every substring of length 1 is a palindrome for (i = 0; i < n; i++) { P[i][i] = true; } /* L is substring length. Build the solution in bottom up manner by considering all substrings of length starting from 2 to n. */ for (L = 2; L <= n; L++) { // For substring of length L, set different possible starting indexes for (i = 0; i < n - L + 1; i++) { j = i + L - 1; // Set ending index // If L is 2, then we just need to compare two characters. Else // need to check two corner characters and value of P[i+1][j-1] if (L == 2) P[i][j] = (str[i] == str[j]); else P[i][j] = (str[i] == str[j]) && P[i + 1][j - 1]; } } for (i = 0; i < n; i++) { if (P[0][i] == true) C[i] = 0; else { C[i] = INT_MAX; for (j = 0; j < i; j++) { if (P[j + 1][i] == true && 1 + C[j] < C[i]) C[i] = 1 + C[j]; } } } // Return the min cut value for complete string. i.e., str[0..n-1] return C[n - 1];}// Driver program to test above functionint main(){ char str[] = "ababbbabbababa"; cout <<"Min cuts needed for Palindrome Partitioning is " << minPalPartion(str); return 0;}// This code is contributed by shivanisinghss2110 |
C
// Dynamic Programming Solution for Palindrome Partitioning Problem#include <limits.h>#include <stdio.h>#include <stdbool.h>#include <string.h>// A utility function to get minimum of two integersint min(int a, int b) { return (a < b) ? a : b; }// Returns the minimum number of cuts needed to partition a string// such that every part is a palindromeint minPalPartion(char* str){ // Get the length of the string int n = strlen(str); /* Create two arrays to build the solution in bottom-up manner C[i] = Minimum number of cuts needed for a palindrome partitioning of substring str[0..i] P[i][j] = true if substring str[i..j] is palindrome, else false Note that C[i] is 0 if P[0][i] is true */ int C[n]; bool P[n][n]; int i, j, k, L; // different looping variables // Every substring of length 1 is a palindrome for (i = 0; i < n; i++) { P[i][i] = true; } /* L is substring length. Build the solution in bottom up manner by considering all substrings of length starting from 2 to n. */ for (L = 2; L <= n; L++) { // For substring of length L, set different possible starting indexes for (i = 0; i < n - L + 1; i++) { j = i + L - 1; // Set ending index // If L is 2, then we just need to compare two characters. Else // need to check two corner characters and value of P[i+1][j-1] if (L == 2) P[i][j] = (str[i] == str[j]); else P[i][j] = (str[i] == str[j]) && P[i + 1][j - 1]; } } for (i = 0; i < n; i++) { if (P[0][i] == true) C[i] = 0; else { C[i] = INT_MAX; for (j = 0; j < i; j++) { if (P[j + 1][i] == true && 1 + C[j] < C[i]) C[i] = 1 + C[j]; } } } // Return the min cut value for complete string. i.e., str[0..n-1] return C[n - 1];}// Driver program to test above functionint main(){ char str[] = "ababbbabbababa"; printf("Min cuts needed for Palindrome Partitioning is %d", minPalPartion(str)); return 0;} |
Java
// Java Code for Palindrome Partitioning// Problempublic class GFG { // Returns the minimum number of cuts needed // to partition a string such that every part // is a palindrome static int minPalPartion(String str) { // Get the length of the string int n = str.length(); /* Create two arrays to build the solution in bottom up manner C[i] = Minimum number of cuts needed for palindrome partitioning of substring str[0..i] P[i][j] = true if substring str[i..j] is palindrome, else false Note that C[i] is 0 if P[0][i] is true */ int[] C = new int[n]; boolean[][] P = new boolean[n][n]; int i, j, k, L; // different looping variables // Every substring of length 1 is a palindrome for (i = 0; i < n; i++) { P[i][i] = true; } /* L is substring length. Build the solution in bottom up manner by considering all substrings of length starting from 2 to n. */ for (L = 2; L <= n; L++) { // For substring of length L, set different // possible starting indexes for (i = 0; i < n - L + 1; i++) { j = i + L - 1; // Set ending index // If L is 2, then we just need to // compare two characters. Else need to // check two corner characters and value // of P[i+1][j-1] if (L == 2) P[i][j] = (str.charAt(i) == str.charAt(j)); else P[i][j] = (str.charAt(i) == str.charAt(j)) && P[i + 1][j - 1]; } } for (i = 0; i < n; i++) { if (P[0][i] == true) C[i] = 0; else { C[i] = Integer.MAX_VALUE; for (j = 0; j < i; j++) { if (P[j + 1][i] == true && 1 + C[j] < C[i]) C[i] = 1 + C[j]; } } } // Return the min cut value for complete // string. i.e., str[0..n-1] return C[n - 1]; } // Driver program to test above function public static void main(String args[]) { String str = "ababbbabbababa"; System.out.println("Min cuts needed for " + "Palindrome Partitioning" + " is " + minPalPartion(str)); }}// This code is contributed by Sumit Ghosh |
Python3
# Dynamic Programming Solution for# Palindrome Partitioning Problemimport sys# Returns the minimum number of cuts# needed to partition a string such# that every part is a palindromedef minPalPartion(str1): # Get the length of the string n = len(str1); # Create two arrays to build the solution # in bottom up manner # C[i] = Minimum number of cuts needed # for palindrome partitioning of # substring str[0..i] # P[i][j] = true if substring str[i..j] # is palindrome, else false # Note that C[i] is 0 if P[0][i] is true C = [0]*(n + 1); P = [[False for x in range(n + 1)] for y in range(n + 1)]; # Every substring of length 1 is # a palindrome for i in range(n): P[i][i] = True; # L is substring length. Build the solution # in bottom up manner by considering all # substrings of length starting from 2 to n. for L in range(2, n + 1): # For substring of length L, set # different possible starting indexes for i in range(n - L + 1): j = i + L - 1; # Set ending index # If L is 2, then we just need to # compare two characters. Else need # to check two corner characters and # value of P[i + 1][j-1] if (L == 2): P[i][j] = (str1[i] == str1[j]); else: P[i][j] = ((str1[i] == str1[j]) and P[i + 1][j - 1]); for i in range(n): if (P[0][i] == True): C[i] = 0; else: C[i] = sys.maxsize; for j in range(i): if(P[j + 1][i] == True and 1 + C[j] < C[i]): C[i] = 1 + C[j]; # Return the min cut value for complete # string. i.e., str[0..n-1] return C[n - 1];# Driver Codestr1 = "ababbbabbababa";print("Min cuts needed for Palindrome Partitioning is", minPalPartion(str1));# This code is contributed by mits |
C#
// C# Code for Palindrome Partitioning// Problemusing System;class GFG { // Returns the minimum number of cuts needed // to partition a string such that every part // is a palindrome static int minPalPartion(String str) { // Get the length of the string int n = str.Length; /* Create two arrays to build the solution in bottom up manner C[i] = Minimum number of cuts needed for palindrome partitioning of substring str[0..i] P[i][j] = true if substring str[i..j] is palindrome, else false Note that C[i] is 0 if P[0][i] is true */ int[] C = new int[n]; bool[, ] P = new bool[n, n]; int i, j, L; // different looping variables // Every substring of length 1 is a palindrome for (i = 0; i < n; i++) { P[i, i] = true; } /* L is substring length. Build the solution in bottom up manner by considering all substrings of length starting from 2 to n. */ for (L = 2; L <= n; L++) { // For substring of length L, set different // possible starting indexes for (i = 0; i < n - L + 1; i++) { j = i + L - 1; // Set ending index // If L is 2, then we just need to // compare two characters. Else need to // check two corner characters and value // of P[i+1][j-1] if (L == 2) P[i, j] = (str[i] == str[j]); else P[i, j] = (str[i] == str[j]) && P[i + 1, j - 1]; } } for (i = 0; i < n; i++) { if (P[0, i] == true) C[i] = 0; else { C[i] = int.MaxValue; for (j = 0; j < i; j++) { if (P[j + 1, i] == true && 1 + C[j] < C[i]) C[i] = 1 + C[j]; } } } // Return the min cut value for complete // string. i.e., str[0..n-1] return C[n - 1]; } // Driver program public static void Main() { String str = "ababbbabbababa"; Console.Write("Min cuts needed for " + "Palindrome Partitioning" + " is " + minPalPartion(str)); }}// This code is contributed by Sam007 |
PHP
<?php// Dynamic Programming Solution for// Palindrome Partitioning Problem// Returns the minimum number of cuts// needed to partition a string such// that every part is a palindromefunction minPalPartion(&$str){ // Get the length of the string $n = strlen($str); /* Create two arrays to build the solution in bottom up manner C[i] = Minimum number of cuts needed for palindrome partitioning of substring str[0..i] P[i][j] = true if substring str[i..j] is palindrome, else false Note that C[i] is 0 if P[0][i] is true */ $C = array_fill(0, $n, 0); $p = array_fill(0, 10, array_fill(0, 10, 0)); // Every substring of length 1 is // a palindrome for ($i = 0; $i < $n; $i++) { $P[$i][$i] = true; } /* L is substring length. Build the solution in bottom up manner by considering all substrings of length starting from 2 to n. */ for ($L = 2; $L <= $n; $L++) { // For substring of length L, set // different possible starting indexes for ($i = 0; $i < $n - $L + 1; $i++) { $j = $i + $L - 1; // Set ending index // If L is 2, then we just need to // compare two characters. Else need // to check two corner characters and // value of P[i+1][j-1] if ($L == 2) $P[$i][$j] = ($str[$i] == $str[$j]); else $P[$i][$j] = ($str[$i] == $str[$j]) && $P[$i + 1][$j - 1]; } } for ($i = 0; $i < $n; $i++) { if ($P[0][$i] == true) $C[$i] = 0; else { $C[$i] = PHP_INT_MAX; for($j = 0; $j < $i; $j++) { if($P[$j + 1][$i] == true && 1 + $C[$j] < $C[$i]) $C[$i] = 1 + $C[$j]; } } } // Return the min cut value for complete // string. i.e., str[0..n-1] return $C[$n - 1];}// Driver Code$str = "ababbbabbababa";echo "Min cuts needed for Palindrome " . "Partitioning is " . minPalPartion($str);// This code is contributed by rathbhupendra?> |
Javascript
<script>// javascript Code for Palindrome Partitioning// Problem // Returns the minimum number of cuts needed // to partition a string such that every part // is a palindrome function minPalPartion(str) { // Get the length of the string var n = str.length; /* * Create two arrays to build the solution in bottom up manner C[i] = Minimum * number of cuts needed for palindrome partitioning of substring str[0..i] * P[i][j] = true if substring str[i..j] is palindrome, else false Note that * C[i] is 0 if P[0][i] is true */ var C = Array(n).fill(0); var P = Array(n).fill().map(()=>Array(n).fill(false)); var i, j, k, L; // different looping variables // Every substring of length 1 is a palindrome for (i = 0; i < n; i++) { P[i][i] = true; } /* * L is substring length. Build the solution in bottom up manner by considering * all substrings of length starting from 2 to n. */ for (L = 2; L <= n; L++) { // For substring of length L, set different // possible starting indexes for (i = 0; i < n - L + 1; i++) { j = i + L - 1; // Set ending index // If L is 2, then we just need to // compare two characters. Else need to // check two corner characters and value // of P[i+1][j-1] if (L == 2) P[i][j] = (str.charAt(i) == str.charAt(j)); else P[i][j] = (str.charAt(i) == str.charAt(j)) && P[i + 1][j - 1]; } } for (i = 0; i < n; i++) { if (P[0][i] == true) C[i] = 0; else { C[i] = Number.MAX_VALUE; for (j = 0; j < i; j++) { if (P[j + 1][i] == true && 1 + C[j] < C[i]) C[i] = 1 + C[j]; } } } // Return the min cut value for complete // string. i.e., str[0..n-1] return C[n - 1]; } // Driver program to test above function var str = "ababbbabbababa"; document.write("Min cuts needed for " + "Palindrome Partitioning" + " is " + minPalPartion(str));// This code is contributed by gauravrajput1</script> |
Output:
Min cuts needed for Palindrome Partitioning is 3
Time Complexity: O(n2)
Auxiliary Space: O(n2)
Using Memorization to solve this problem.
The basic idea is to cache the intermittent results calculated in recursive functions. We can put these results into a hashmap/unordered_map.
To calculate the keys for the Hashmap we will use the starting and end index of the string as the key i.e. [“start_index”.append(“end_index”)] would be the key for the Hashmap.
Below is the implementation of above approach :
C++
// Using memoizatoin to solve the partition problem.#include <bits/stdc++.h>using namespace std;// Function to check if input string is palindrome or notbool ispalindrome(string input, int start, int end){ // Using two pointer technique to check palindrome while (start < end) { if (input[start] != input[end]) return false; start++; end--; } return true;}// Function to find keys for the Hashmapstring convert(int a, int b){ return to_string(a) + "" + to_string(b);}// Returns the minimum number of cuts needed to partition a string// such that every part is a palindromeint minpalparti_memo(string input, int i, int j, unordered_map<string, int>& memo){ if (i > j) return 0; // Key for the Input String string ij = convert(i, j); // If the no of partitions for string "ij" is already calculated // then return the calculated value using the Hashmap if (memo.find(ij) != memo.end()) { return memo[ij]; } // Every String of length 1 is a palindrome if (i == j) { memo[ij] = 0; return 0; } if (ispalindrome(input, i, j)) { memo[ij] = 0; return 0; } int minimum = INT_MAX; // Make a cut at every possible location starting from i to j for (int k = i; k < j; k++) { int left_min = INT_MAX; int right_min = INT_MAX; string left = convert(i, k); string right = convert(k + 1, j); // If left cut is found already if (memo.find(left) != memo.end()) { left_min = memo[left]; } // If right cut is found already if (memo.find(right) != memo.end()) { right_min = memo[right]; } // Recursively calculating for left and right strings if (left_min == INT_MAX) left_min = minpalparti_memo(input, i, k, memo); if (right_min == INT_MAX) right_min = minpalparti_memo(input, k + 1, j, memo); // Taking minimum of all k possible cuts minimum = min(minimum, left_min + 1 + right_min); } memo[ij] = minimum; // Return the min cut value for complete string. return memo[ij];}int main(){ string input = "ababbbabbababa"; unordered_map<string, int> memo; cout << minpalparti_memo(input, 0, input.length() - 1, memo) << endl; return 0;} |
Java
/*package whatever //do not write package name here */import java.io.*;import java.util.*;class GFG { // Using memoizatoin to solve the partition problem.// Function to check if input string is palindrome or notstatic boolean ispalindrome(String input, int start, int end){ // Using two pointer technique to check palindrome while (start < end) { if (input.charAt(start) != input.charAt(end)) return false; start++; end--; } return true;}// Function to find keys for the Hashmapstatic String convert(int a, int b){ return String.valueOf(a) + "" + String.valueOf(b);}// Returns the minimum number of cuts needed to partition a string// such that every part is a palindromestatic int minpalparti_memo(String input, int i, int j, HashMap<String, Integer> memo){ if (i > j) return 0; // Key for the Input String String ij = convert(i, j); // If the no of partitions for string "ij" is already calculated // then return the calculated value using the Hashmap if (memo.containsKey(ij)) { return memo.get(ij); } // Every String of length 1 is a palindrome if (i == j) { memo.put(ij, 0); return 0; } if (ispalindrome(input, i, j)) { memo.put(ij, 0); return 0; } int minimum = Integer.MAX_VALUE; // Make a cut at every possible location starting from i to j for (int k = i; k < j; k++) { int left_min = Integer.MAX_VALUE; int right_min = Integer.MAX_VALUE; String left = convert(i, k); String right = convert(k + 1, j); // If left cut is found already if (memo.containsKey(left)) { left_min = memo.get(left); } // If right cut is found already if (memo.containsKey(right)) { right_min = memo.get(right); } // Recursively calculating for left and right strings if (left_min == Integer.MAX_VALUE) left_min = minpalparti_memo(input, i, k, memo); if (right_min == Integer.MAX_VALUE) right_min = minpalparti_memo(input, k + 1, j, memo); // Taking minimum of all k possible cuts minimum = Math.min(minimum, left_min + 1 + right_min); } memo.put(ij, minimum); // Return the min cut value for complete string. return memo.get(ij);} public static void main(String args[]){ String input = "ababbbabbababa"; HashMap<String, Integer> memo = new HashMap<>(); System.out.println(minpalparti_memo(input, 0, input.length() - 1, memo));}}// code is contributed by shinjanpatra |
Python3
# Using memoizatoin to solve the partition problem.# Function to check if input string is palindrome or notdef ispalindrome(input, start, end): # Using two pointer technique to check palindrome while (start < end): if (input[start] != input[end]): return False; start += 1 end -= 1 return True;# Function to find keys for the Hashmapdef convert(a, b): return str(a) + str(b);# Returns the minimum number of cuts needed to partition a string# such that every part is a palindromedef minpalparti_memo(input, i, j, memo): if (i > j): return 0; # Key for the Input String ij = convert(i, j); # If the no of partitions for string "ij" is already calculated # then return the calculated value using the Hashmap if (ij in memo): return memo[ij]; # Every String of length 1 is a palindrome if (i == j): memo[ij] = 0; return 0; if (ispalindrome(input, i, j)): memo[ij] = 0; return 0; minimum = 1000000000 # Make a cut at every possible location starting from i to j for k in range(i, j): left_min = 1000000000 right_min = 1000000000 left = convert(i, k); right = convert(k + 1, j); # If left cut is found already if (left in memo): left_min = memo[left]; # If right cut is found already if (right in memo): right_min = memo[right]; # Recursively calculating for left and right strings if (left_min == 1000000000): left_min = minpalparti_memo(input, i, k, memo); if (right_min == 1000000000): right_min = minpalparti_memo(input, k + 1, j, memo); # Taking minimum of all k possible cuts minimum = min(minimum, left_min + 1 + right_min); memo[ij] = minimum; # Return the min cut value for complete string. return memo[ij]; # Driver codeif __name__=='__main__': input = "ababbbabbababa"; memo = dict() print(minpalparti_memo(input, 0, len(input) - 1, memo)) # This code is contributed by Pratham76. |
C#
// C# code for the above approachusing System;using System.Collections.Generic;class GFG { // Using memoizatoin to solve the partition problem. // Function to check if input string is palindrome or // not static bool ispalindrome(string input, int start, int end) { // Using two pointer technique to check palindrome while (start < end) { if (input[start] != input[end]) return false; start++; end--; } return true; } // Function to find keys for the Hashmap static string convert(int a, int b) { return a.ToString() + "" + b.ToString(); } // Returns the minimum number of cuts needed to // partition a string such that every part is a // palindrome static int minpalparti_memo(string input, int i, int j, Dictionary<string, int> memo) { if (i > j) return 0; // Key for the Input String string ij = convert(i, j); // If the no of partitions for string "ij" is // already calculated then return the calculated // value using the Hashmap if (memo.ContainsKey(ij)) { return memo[ij]; } // Every String of length 1 is a palindrome if (i == j) { memo.Add(ij, 0); return 0; } if (ispalindrome(input, i, j)) { memo.Add(ij, 0); return 0; } int minimum = int.MaxValue; // Make a cut at every possible location starting // from i to j for (int k = i; k < j; k++) { int left_min = int.MaxValue; int right_min = int.MaxValue; string left = convert(i, k); string right = convert(k + 1, j); // If left cut is found already if (memo.ContainsKey(left)) { left_min = memo[left]; } // If right cut is found already if (memo.ContainsKey(right)) { right_min = memo[right]; } // Recursively calculating for left and right // strings if (left_min == int.MaxValue) left_min = minpalparti_memo(input, i, k, memo); if (right_min == int.MaxValue) right_min = minpalparti_memo(input, k + 1, j, memo); // Taking minimum of all k possible cuts minimum = Math.Min(minimum, left_min + 1 + right_min); } memo.Add(ij, minimum); // Return the min cut value for complete string. return memo[ij]; } public static void Main(string[] args) { string input = "ababbbabbababa"; var memo = new Dictionary<string, int>(); Console.WriteLine(minpalparti_memo( input, 0, input.Length - 1, memo)); }}// This code is contributed by lokeshpotta20. |
Javascript
<script>// Using memoizatoin to solve the partition problem.// Function to check if input string is palindrome or notfunction ispalindrome(input,start,end){ // Using two pointer technique to check palindrome while (start < end) { if (input[start] != input[end]) return false; start++; end--; } return true;}// Function to find keys for the Hashmapfunction convert(a,b){ return a.toString() + "" + b.toString();}// Returns the minimum number of cuts needed to partition a string// such that every part is a palindromefunction minpalparti_memo(input, i, j, memo){ if (i > j) return 0; // Key for the Input String let ij = convert(i, j); // If the no of partitions for string "ij" is already calculated // then return the calculated value using the Hashmap if (memo.has(ij)) { return memo.get(ij); } // Every String of length 1 is a palindrome if (i == j) { memo.set(ij, 0); return 0; } if (ispalindrome(input, i, j)) { memo.set(ij,0); return 0; } let minimum = Number.MAX_VALUE // Make a cut at every possible location starting from i to j for (let k = i; k < j; k++) { let left_min = Number.MAX_VALUE; let right_min = Number.MAX_VALUE; let left = convert(i, k); let right = convert(k + 1, j); // If left cut is found already if (memo.has(left) == true) { left_min = memo.get(left); } // If right cut is found already if (memo.has(right) == true) { right_min = memo.get(right); } // Recursively calculating for left and right strings if (left_min == Number.MAX_VALUE) left_min = minpalparti_memo(input, i, k, memo); if (right_min == Number.MAX_VALUE) right_min = minpalparti_memo(input, k + 1, j, memo); // Taking minimum of all k possible cuts minimum = Math.min(minimum, left_min + 1 + right_min); } memo.set(ij, minimum); // Return the min cut value for complete string. return memo.get(ij);}// driver codelet input = "ababbbabbababa";let memo = new Map();document.write(minpalparti_memo(input, 0, input.length - 1, memo),"</br>");// This code is contributed by shinjanpatra.</script> |
Time Complexity: O(n3)
Auxiliary Space: O(n2)
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