Given two strings and
. Find the longest common prefix between them after performing zero or more operation on string
. In each operation, you can swap any two letters.
Examples:
Input : a = "here", b = "there" Output : 4 The 2nd string can be made "heret" by just swapping characters and thus the longest prefix is of length 4. Input : a = "you", b = "me" Output : 0
Given that we are only allowed to performs swaps in the string and the length of prefix should be maximized. So the idea is to traverse string
and check if the frequency of current character in string
is same or less of that in string
. If yes then move forward in string
otherwise break and print the length of the part of string a up to which a character is matched in string
.
Below is the implementation of the above approach:
C++
// C++ program to find the longest // common prefix between two strings // after performing swaps on the second string #include <bits/stdc++.h> using namespace std; void LengthLCP(string x, string y) { int fr[26]={0}; int a = x.length(); // length of x int b = y.length(); // length of y for ( int i=0 ;i<b ; i++) { // creating frequency array of // characters of y fr[y[i] - 97] += 1; } // storing the length of // longest common prefix int c = 0; for ( int i=0 ;i<a ; i++) { // checking if the frequency of the character at // position i in x in b is greater than zero or not // if zero we increase the prefix count by 1 if (fr[x[i] - 97] > 0){ c += 1; fr[x[i] - 97] -= 1; } else break ; } cout<<(c)<<endl; } // Driver Code int main() { string x= "here" , y = "there" ; LengthLCP(x, y); return 0; } //contributed by Arnab Kundu |
Java
// Java program to find the longest // common prefix between two strings // after performing swaps on the second string public class GFG { static void LengthLCP(String x, String y) { int fr[]= new int [ 26 ]; int a = x.length(); // length of x int b = y.length(); // length of y for ( int i= 0 ;i<b ; i++) { // creating frequency array of // characters of y fr[y.charAt(i) - 97 ] += 1 ; } // storing the length of // longest common prefix int c = 0 ; for ( int i= 0 ;i<a ; i++) { // checking if the frequency of the character at // position i in x in b is greater than zero or not // if zero we increase the prefix count by 1 if (fr[x.charAt(i) - 97 ] > 0 ){ c += 1 ; fr[x.charAt(i) - 97 ] -= 1 ; } else break ; } System.out.println((c)) ; } public static void main(String args[]) { String x= "here" , y = "there" ; LengthLCP(x, y); } // This code is contributed by ANKITRAI1 } |
Python3
# Python program to find the longest # common prefix between two strings # after performing swaps on the second string def LengthLCP(x, y): fr = [ 0 ] * 26 a = len (x) # length of x b = len (y) # length of y for i in range (b): # creating frequency array of # characters of y fr[ ord (y[i]) - 97 ] + = 1 # storing the length of # longest common prefix c = 0 for i in range (a): # checking if the frequency of the character at # position i in x in b is greater than zero or not # if zero we increase the prefix count by 1 if (fr[ ord (x[i]) - 97 ] > 0 ): c + = 1 fr[ ord (x[i]) - 97 ] - = 1 else : break print (c) # Driver Code x, y = "here" , "there" LengthLCP(x, y) |
C#
// C# program to find the longest // common prefix between two strings // after performing swaps on the // second string using System; class GFG { static void LengthLCP(String x, String y) { int []fr = new int [26]; int a = x.Length; // length of x int b = y.Length; // length of y for ( int i = 0 ; i < b; i++) { // creating frequency array // of characters of y fr[y[i] - 97] += 1; } // storing the length of // longest common prefix int c = 0; for ( int i = 0 ; i < a; i++) { // checking if the frequency of // the character at position i // in x in b is greater than zero // or not if zero we increase the // prefix count by 1 if (fr[x[i] - 97] > 0) { c += 1; fr[x[i] - 97] -= 1; } else break ; } Console.Write((c)) ; } // Driver Code public static void Main() { String x = "here" , y = "there" ; LengthLCP(x, y); } } // This code is contributed by 29AjayKumar |
PHP
<?php // PHP program to find the longest // common prefix between two strings // after performing swaps on the second string function LengthLCP( $x , $y ) { $fr = array_fill (0,26,NULL); $a = strlen ( $x ); // length of x $b = strlen ( $y ); // length of y for ( $i = 0 ; $i < $b ; $i ++) { // creating frequency array of // characters of y $fr [ord( $y [ $i ]) - 97] += 1; } // storing the length of // longest common prefix $c = 0; for ( $i = 0 ; $i < $a ; $i ++) { // checking if the frequency of the character at // position i in x in b is greater than zero or not // if zero we increase the prefix count by 1 if ( $fr [ord( $x [ $i ]) - 97] > 0) { $c += 1; $fr [ord( $x [ $i ]) - 97] -= 1; } else break ; } echo $c ; } // Driver Code $x = "here" ; $y = "there" ; LengthLCP( $x , $y ); return 0; // This code is contributed by ChitraNayal ?> |
4
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