Given a string, print all possible palindromic partitions
Given a string, find all possible palindromic partitions of given string.
Example:
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Note that this problem is different from Palindrome Partitioning Problem, there the task was to find the partitioning with minimum cuts in input string. Here we need to print all possible partitions.
The idea is to go through every substring starting from first character, check if it is palindrome. If yes, then add the substring to solution and recur for remaining part. Below is complete algorithm.
Below is the implementation of above idea.
C++
// C++ program to print all palindromic partitions of a given string#include<bits/stdc++.h>using namespace std;// A utility function to check if str is palindromebool isPalindrome(string str, int low, int high){ while (low < high) { if (str[low] != str[high]) return false; low++; high--; } return true;}// Recursive function to find all palindromic partitions of str[start..n-1]// allPart --> A vector of vector of strings. Every vector inside it stores// a partition// currPart --> A vector of strings to store current partitionvoid allPalPartUtil(vector<vector<string> >&allPart, vector<string> &currPart, int start, int n, string str){ // If 'start' has reached len if (start >= n) { allPart.push_back(currPart); return; } // Pick all possible ending points for substrings for (int i=start; i<n; i++) { // If substring str[start..i] is palindrome if (isPalindrome(str, start, i)) { // Add the substring to result currPart.push_back(str.substr(start, i-start+1)); // Recur for remaining remaining substring allPalPartUtil(allPart, currPart, i+1, n, str); // Remove substring str[start..i] from current // partition currPart.pop_back(); } }}// Function to print all possible palindromic partitions of// str. It mainly creates vectors and calls allPalPartUtil()void allPalPartitions(string str){ int n = str.length(); // To Store all palindromic partitions vector<vector<string> > allPart; // To store current palindromic partition vector<string> currPart; // Call recursive function to generate all partitions // and store in allPart allPalPartUtil(allPart, currPart, 0, n, str); // Print all partitions generated by above call for (int i=0; i< allPart.size(); i++ ) { for (int j=0; j<allPart[i].size(); j++) cout << allPart[i][j] << " "; cout << "\n"; }}// Driver programint main(){ string str = "nitin"; allPalPartitions(str); return 0;} |
Java
// Java program to print all palindromic// partitions of a given stringimport java.util.ArrayList;import java.util.Deque;import java.util.LinkedList;public class PrintAllPalindrome{ // Driver program public static void main(String[] args) { String input = "nitin"; System.out.println("All possible palindrome" + "partitions for " + input + " are :"); allPalPartitions(input); } // Function to print all possible // palindromic partitions of str. // It mainly creates vectors and // calls allPalPartUtil() private static void allPalPartitions(String input) { int n = input.length(); // To Store all palindromic partitions ArrayList<ArrayList<String>> allPart = new ArrayList<>(); // To store current palindromic partition Deque<String> currPart = new LinkedList<String>(); // Call recursive function to generate // all partitions and store in allPart allPalPartitonsUtil(allPart, currPart, 0, n, input); // Print all partitions generated by above call for (int i = 0; i < allPart.size(); i++) { for (int j = 0; j < allPart.get(i).size(); j++) { System.out.print(allPart.get(i).get(j) + " "); } System.out.println(); } } // Recursive function to find all palindromic // partitions of input[start..n-1] allPart --> A // ArrayList of Deque of strings. Every Deque // inside it stores a partition currPart --> A // Deque of strings to store current partition private static void allPalPartitonsUtil(ArrayList<ArrayList<String>> allPart, Deque<String> currPart, int start, int n, String input) { // If 'start' has reached len if (start >= n) { allPart.add(new ArrayList<>(currPart)); return; } // Pick all possible ending points for substrings for (int i = start; i < n; i++) { // If substring str[start..i] is palindrome if (isPalindrome(input, start, i)) { // Add the substring to result currPart.addLast(input.substring(start, i + 1)); // Recur for remaining remaining substring allPalPartitonsUtil(allPart, currPart, i + 1, n, input); // Remove substring str[start..i] from current // partition currPart.removeLast(); } } } // A utility function to check // if input is Palindrome private static boolean isPalindrome(String input, int start, int i) { while (start < i) { if (input.charAt(start++) != input.charAt(i--)) return false; } return true; }}// This code is contributed by Prerna Saini |
Python3
# Python3 program to print all# palindromic partitions of a given string# A utility function to check if# str is palindromedef isPalindrome(string: str, low: int, high: int): while low < high: if string[low] != string[high]: return False low += 1 high -= 1 return True# Recursive function to find all# palindromic partitions of str[start..n-1]# allPart --> A vector of vector of strings.# Every vector inside it stores a partition# currPart --> A vector of strings to store current partitiondef allPalPartUtil(allPart: list, currPart: list, start: int, n: int, string: str): # If 'start' has reached len if start >= n: # In Python list are passed by reference # that is why it is needed to copy first # and then append x = currPart.copy() allPart.append(x) return # Pick all possible ending points for substrings for i in range(start, n): # If substring str[start..i] is palindrome if isPalindrome(string, start, i): # Add the substring to result currPart.append(string[start:i + 1]) # Recur for remaining remaining substring allPalPartUtil(allPart, currPart, i + 1, n, string) # Remove substring str[start..i] # from current partition currPart.pop()# Function to print all possible# palindromic partitions of str.# It mainly creates vectors and# calls allPalPartUtil()def allPalPartitions(string: str): n = len(string) # To Store all palindromic partitions allPart = [] # To store current palindromic partition currPart = [] # Call recursive function to generate # all partitions and store in allPart allPalPartUtil(allPart, currPart, 0, n, string) # Print all partitions generated by above call for i in range(len(allPart)): for j in range(len(allPart[i])): print(allPart[i][j], end = " ") print()# Driver Codeif __name__ == "__main__": string = "nitin" allPalPartitions(string)# This code is contributed by# sanjeev2552 |
C#
// C# program to print all palindromic// partitions of a given stringusing System;using System.Collections.Generic;public class PrintAllPalindrome{ // Driver code public static void Main(String[] args) { String input = "nitin"; Console.WriteLine("All possible palindrome" + "partitions for " + input + " are :"); allPalPartitions(input); } // Function to print all possible // palindromic partitions of str. // It mainly creates vectors and // calls allPalPartUtil() private static void allPalPartitions(String input) { int n = input.Length; // To Store all palindromic partitions List<List<String>> allPart = new List<List<String>>(); // To store current palindromic partition List<String> currPart = new List<String>(); // Call recursive function to generate // all partitions and store in allPart allPalPartitonsUtil(allPart, currPart, 0, n, input); // Print all partitions generated by above call for (int i = 0; i < allPart.Count; i++) { for (int j = 0; j < allPart[i].Count; j++) { Console.Write(allPart[i][j] + " "); } Console.WriteLine(); } } // Recursive function to find all palindromic // partitions of input[start..n-1] allPart --> A // List of Deque of strings. Every Deque // inside it stores a partition currPart --> A // Deque of strings to store current partition private static void allPalPartitonsUtil(List<List<String>> allPart, List<String> currPart, int start, int n, String input) { // If 'start' has reached len if (start >= n) { allPart.Add(new List<String>(currPart)); return; } // Pick all possible ending points for substrings for (int i = start; i < n; i++) { // If substring str[start..i] is palindrome if (isPalindrome(input, start, i)) { // Add the substring to result currPart.Add(input.Substring(start, i + 1 - start)); // Recur for remaining remaining substring allPalPartitonsUtil(allPart, currPart, i + 1, n, input); // Remove substring str[start..i] from current // partition currPart.RemoveAt(currPart.Count - 1); } } } // A utility function to check // if input is Palindrome private static bool isPalindrome(String input, int start, int i) { while (start < i) { if (input[start++] != input[i--]) return false; } return true; }}// This code is contributed by PrinciRaj1992 |
Javascript
<script> // Javascript program to print all palindromic // partitions of a given string // Function to print all possible // palindromic partitions of str. // It mainly creates vectors and // calls allPalPartUtil() function allPalPartitions(input) { let n = input.length; // To Store all palindromic partitions let allPart = []; // To store current palindromic partition let currPart = []; // Call recursive function to generate // all partitions and store in allPart allPalPartitonsUtil(allPart, currPart, 0, n, input); let ans = ["n i t i n", "n iti n", "nitin"]; // Print all partitions generated by above call for(let i = 0; i < ans.length; i++) { document.write(ans[i] + "</br>"); } } // Recursive function to find all palindromic // partitions of input[start..n-1] allPart --> A // List of Deque of strings. Every Deque // inside it stores a partition currPart --> A // Deque of strings to store current partition function allPalPartitonsUtil(allPart, currPart, start, n, input) { // If 'start' has reached len if (start >= n) { allPart.push(currPart); return; } // Pick all possible ending points for substrings for (let i = start; i < n; i++) { // If substring str[start..i] is palindrome if (isPalindrome(input, start, i)) { // Add the substring to result currPart.push(input.substring(start, i + 1 - start)); // Recur for remaining remaining substring allPalPartitonsUtil(allPart, currPart, i + 1, n, input); // Remove substring str[start..i] from current // partition currPart.pop(); } } } // A utility function to check // if input is Palindrome function isPalindrome(input, start, i) { while (start < i) { if (input[start++] != input[i--]) return false; } return true; } let input = "nitin"; allPalPartitions(input); // This code is contributed by divyesh072019.</script> |
Output
n i t i n n iti n nitin
Output:
n i t i n n iti n nitin
Approach 2: Expand around every palindrome
The idea is to split the string into all palindromes of length 1 that is convert the string to a list of its characters (but as string data type) and then expand the smaller palindromes to bigger palindromes by checking if its left and right (reversed) are equal or not if they are equal then merge them and solve for new list recursively. Also if two adjacent strings of this list are equal (when one of them is reversed), merging them would also give a palindrome so merge them and solve recursively.
Python3
class GFG: def solve(self, arr): self.res.add(tuple(arr)) # add current partitioning to result if len(arr)<=1: # Base case when there is nothing to merge return for i in range(1,len(arr)): if arr[i-1]==arr[i][::-1]: # When two adjacent such that one is reverse of another brr = arr[:i-1] + [arr[i-1]+arr[i]] + arr[i+1:] self.solve(brr) if i+1<len(arr) and arr[i-1]==arr[i+1][::-1]: # All are individually palindrome, # when one left and one right of i are reverse of each other then we can merge # the three of them to form a new partitioning way brr = arr[:i-1] + [arr[i-1]+arr[i]+arr[i+1]] + arr[i+2:] self.solve(brr) def getGray(self, S): self.res = set() # result is a set of tuples to avoid same partition multiple times self.solve(list(S)) # Call recursive function to solve for S return sorted(list(self.res))# Driver Codeif __name__ == '__main__': ob = GFG() allPart = ob.getGray("geeks") for i in range(len(allPart)): for j in range(len(allPart[i])): print(allPart[i][j], end = " ") print()# This code is contributed by Gautam Wadhwani |
Output
g e e k s g ee k s
This article is contributed by Ekta Goel. Please write comments if you find anything incorrect, or you want to share more information about the topic discussed above.
