Given three strings A, B, and C of equal length, the task is to find the minimum number of swap operations that can be performed such that the strings A and B become equal when any swapping can be done only with C.
Examples:
Input: A = “xyz”, B = “yzx”, C = “yzx”
Output: 3
Explanation:
Swap all the characters of string C with string A one by one
Input: A = “pqr”, B = “stu”, C = “vwx”
Output: -1
Explanation
It’s impossible to make strings A and B equal, even by using C
Approach: Since the lengths of the strings are equal, the idea is to traverse the strings and check for the characters present in the strings.
For every index ‘i’, the following cases occur:
- If the character at the given index for the string A is the same as the character in B, then we can proceed to check the next character.
- If the character at the given index for the string A and B are not equal, then we check if the character at strings B and C or A and C are equal, and accordingly, we swap those characters.
- If none of the above conditions satisfies, then it’s impossible to make the strings A and B equal.
Below is the implementation of the above approach:
C++
// C++ implementation to find the // minimum number of swaps to make // two strings equal #include <bits/stdc++.h> using namespace std; // Function to swap the characters void swap( char & x, char & y) { char temp = x; x = y; y = temp; } // Function to find the minimum number of swaps // to make two strings equal void swapOperations(string a, string b, string c) { // Counting length of string int l = a.length(); int i = 0; // Initializing the answer int total_swaps = 0; // For loop to iterate through the // given strings for (i = 0; i < l; i++) { // Condition if both character of // string a and b are equal if (a[i] == b[i]) continue ; // Condition if character of // string a and c are equal if (a[i] == c[i]) { // If yes, then swap // the characters swap(b[i], c[i]); total_swaps++; continue ; } // Condition if character of // string b and c are equal if (b[i] == c[i]) { // If yes, then swap // the characters swap(a[i], c[i]); total_swaps++; continue ; } // Else, it is impossible to make // both the strings equal break ; } // Printing the answer if (i == l) cout << total_swaps << endl; else cout << -1 << endl; } // Driver Code int main() { string a = "xyz" ; string b = "yzx" ; string c = "yzx" ; swapOperations(a, b, c); return 0; } |
Java
// Java implementation to find the // minimum number of swaps to make // two strings equal class GFG { // Function to find the minimum number of swaps // to make two strings equal static void swapOperations( char []a, char []b, char []c) { // Counting length of string int l = a.length; int i = 0 ; // Initializing the answer int total_swaps = 0 ; char temp; // For loop to iterate through the // given strings for (i = 0 ; i < l; i++) { // Condition if both character of // string a and b are equal if (a[i] == b[i]) continue ; // Condition if character of // string a and c are equal if (a[i] == c[i]) { // If yes, then swap // the characters // swap(b[i], c[i]); temp = b[i]; b[i] = c[i]; c[i] = temp; total_swaps++; continue ; } // Condition if character of // string b and c are equal if (b[i] == c[i]) { // If yes, then swap // the characters //swap(a[i], c[i]); temp = a[i]; a[i] = c[i]; c[i] = temp; total_swaps++; continue ; } // Else, it is impossible to make // both the strings equal break ; } // Printing the answer if (i == l) System.out.println(total_swaps) ; else System.out.println(- 1 ) ; } // Driver Code public static void main (String[] args) { String a = "xyz" ; String b = "yzx" ; String c = "yzx" ; swapOperations(a.toCharArray(), b.toCharArray(), c.toCharArray()); } } // This code is contributed by Yash_R |
Python3
# Python3 implementation to find the # minimum number of swaps to make # two strings equal # Function to find the minimum number of swaps # to make two strings equal def swapOperations(a, b, c) : # Counting length of string l = len (a); i = 0 ; # Initializing the answer total_swaps = 0 ; # For loop to iterate through the # given strings for i in range (l) : # Condition if both character of # string a and b are equal if (a[i] = = b[i]) : continue ; # Condition if character of # string a and c are equal if (a[i] = = c[i]) : # If yes, then swap # the characters #swap(b[i], c[i]); b[i], c[i] = c[i], b[i]; total_swaps + = 1 ; continue ; # Condition if character of # string b and c are equal if (b[i] = = c[i]) : # If yes, then swap # the characters # swap(a[i], c[i]); a[i], c[i] = c[i], a[i]; total_swaps + = 1 ; continue ; # Else, it is impossible to make # both the strings equal break ; i + = 1 ; # Printing the answer if (i = = l) : print (total_swaps) ; else : print ( - 1 ); # Driver Code if __name__ = = "__main__" : a = "xyz" ; b = "yzx" ; c = "yzx" ; swapOperations( list (a), list (b), list (c)); # This code is contributed by AnkitRai01 |
C#
// C# implementation to find the // minimum number of swaps to make // two strings equal using System; class GFG { // Function to find the minimum number of swaps // to make two strings equal static void swapOperations( char []a, char []b, char []c) { // Counting length of string int l = a.Length; int i = 0; // Initializing the answer int total_swaps = 0; char temp; // For loop to iterate through the // given strings for (i = 0; i < l; i++) { // Condition if both character of // string a and b are equal if (a[i] == b[i]) continue ; // Condition if character of // string a and c are equal if (a[i] == c[i]) { // If yes, then swap // the characters // swap(b[i], c[i]); temp = b[i]; b[i] = c[i]; c[i] = temp; total_swaps++; continue ; } // Condition if character of // string b and c are equal if (b[i] == c[i]) { // If yes, then swap // the characters //swap(a[i], c[i]); temp = a[i]; a[i] = c[i]; c[i] = temp; total_swaps++; continue ; } // Else, it is impossible to make // both the strings equal break ; } // Printing the answer if (i == l) Console.WriteLine(total_swaps) ; else Console.WriteLine(-1) ; } // Driver Code public static void Main( string [] args) { string a = "xyz" ; string b = "yzx" ; string c = "yzx" ; swapOperations(a.ToCharArray(), b.ToCharArray(), c.ToCharArray()); } } // This code is contributed by Yash_R |
Javascript
<script> // JavaScript implementation to find the // minimum number of swaps to make // two strings equal // Function to find the minimum number of swaps // to make two strings equal function swapOperations(a, b, c) { // Counting length of string var l = a.length; var i = 0; // Initializing the answer var total_swaps = 0; // For loop to iterate through the // given strings for (i = 0; i < l; i++) { // Condition if both character of // string a and b are equal if (a[i] === b[i]) continue ; // Condition if character of // string a and c are equal if (a[i] === c[i]) { // If yes, then swap // the characters // swap(b[i], c[i]); var temp = b[i]; b[i] = c[i]; c[i] = temp; total_swaps++; continue ; } // Condition if character of // string b and c are equal if (b[i] === c[i]) { // If yes, then swap // the characters //swap(a[i], c[i]); var temp = a[i]; a[i] = c[i]; c[i] = temp; total_swaps++; continue ; } // Else, it is impossible to make // both the strings equal break ; } // Printing the answer if (i === l) document.write(total_swaps); else document.write(-1); } // Driver Code var a = "xyz" ; var b = "yzx" ; var c = "yzx" ; swapOperations(a.split( "" ), b.split( "" ), c.split( "" )); </script> |
3
Time Complexity: O(l), where l is the size of the given string a
Auxiliary Space: O(1), as no extra space is used
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