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# Check if two strings can be made equal by swapping one character among each other

• Difficulty Level : Basic
• Last Updated : 10 Jun, 2021

Given two strings A and B of length N, the task is to check whether the two strings can be made equal by swapping any character of A with any other character of B only once.
Examples:

Input: A = “SEEKSFORGEEKS”, B = “GEEKSFORGEEKG”
Output: Yes
SEEKSFORGEEKS” and “GEEKSFORGEEKG”
can be swapped to make both the strings equal.
Input: A = “GEEKSFORGEEKS”, B = “THESUPERBSITE”
Output: No

Approach: First omit the elements which are the same and have the same index in both the strings. Then if the new strings are of length two and both the elements in each string are the same then only the swap is possible.
Below is the implementation of the above approach:

## C++

 `// C++ implementation of the approach``#include ``using` `namespace` `std;` `// Function that returns true if the string``// can be made equal after one swap``bool` `canBeEqual(string a, string b, ``int` `n)``{``    ``// A and B are new a and b``    ``// after we omit the same elements``    ``vector<``char``> A, B;` `    ``// Take only the characters which are``    ``// different in both the strings``    ``// for every pair of indices``    ``for` `(``int` `i = 0; i < n; i++)``    ``{` `        ``// If the current characters differ``        ``if` `(a[i]!= b[i])``        ``{``            ``A.push_back(a[i]);``            ``B.push_back(b[i]);``        ``}``    ``}``    ` `    ``// The strings were already equal``    ``if` `(A.size() == B.size() and``        ``B.size() == 0)``        ``return` `true``;` `    ``// If the lengths of the``    ``// strings are two``    ``if` `(A.size() == B.size() and``        ``B.size() == 2)``    ``{` `        ``// If swapping these characters``        ``// can make the strings equal``        ``if` `(A == A and B == B)``            ``return` `true``;``    ``}``    ``return` `false``;``}` `// Driver code``int` `main()``{``    ``string A = ``"SEEKSFORGEEKS"``;``    ``string B = ``"GEEKSFORGEEKG"``;``    ` `    ``if` `(canBeEqual(A, B, A.size()))``        ``printf``(``"Yes"``);``    ``else``        ``printf``(``"No"``);``}` `// This code is contributed by Mohit Kumar`

## Java

 `// Java implementation of the approach``import` `java.util.*;``class` `GFG``{``    ` `// Function that returns true if the string``// can be made equal after one swap``static` `boolean` `canBeEqual(``char` `[]a,``                          ``char` `[]b, ``int` `n)``{``    ``// A and B are new a and b``    ``// after we omit the same elements``    ``Vector A = ``new` `Vector<>();``    ``Vector B = ``new` `Vector<>();` `    ``// Take only the characters which are``    ``// different in both the strings``    ``// for every pair of indices``    ``for` `(``int` `i = ``0``; i < n; i++)``    ``{` `        ``// If the current characters differ``        ``if` `(a[i] != b[i])``        ``{``            ``A.add(a[i]);``            ``B.add(b[i]);``        ``}``    ``}``    ` `    ``// The strings were already equal``    ``if` `(A.size() == B.size() &&``        ``B.size() == ``0``)``        ``return` `true``;` `    ``// If the lengths of the``    ``// strings are two``    ``if` `(A.size() == B.size() &&``        ``B.size() == ``2``)``    ``{` `        ``// If swapping these characters``        ``// can make the strings equal``        ``if` `(A.get(``0``) == A.get(``1``) &&``            ``B.get(``0``) == B.get(``1``))``            ``return` `true``;``    ``}``    ``return` `false``;``}` `// Driver code``public` `static` `void` `main(String[] args)``{``    ``char` `[]A = ``"SEEKSFORGEEKS"``.toCharArray();``    ``char` `[]B = ``"GEEKSFORGEEKG"``.toCharArray();``    ` `    ``if` `(canBeEqual(A, B, A.length))``        ``System.out.printf(``"Yes"``);``    ``else``        ``System.out.printf(``"No"``);``}``}` `// This code is contributed by Rajput-Ji`

## Python3

 `# Python3 implementation of the approach` `# Function that returns true if the string``# can be made equal after one swap``def` `canBeEqual(a, b, n):``    ``# A and B are new a and b``    ``# after we omit the same elements``    ``A ``=``[]``    ``B ``=``[]``    ` `    ``# Take only the characters which are``    ``# different in both the strings``    ``# for every pair of indices``    ``for` `i ``in` `range``(n):``    ` `        ``# If the current characters differ``        ``if` `a[i]!``=` `b[i]:``            ``A.append(a[i])``            ``B.append(b[i])``            ` `    ``# The strings were already equal``    ``if` `len``(A)``=``=` `len``(B)``=``=` `0``:``        ``return` `True``    ` `    ``# If the lengths of the``    ``# strings are two``    ``if` `len``(A)``=``=` `len``(B)``=``=` `2``:``    ` `        ``# If swapping these characters``        ``# can make the strings equal``        ``if` `A[``0``]``=``=` `A[``1``] ``and` `B[``0``]``=``=` `B[``1``]:``            ``return` `True``    ` `    ``return` `False` `# Driver code``A ``=` `'SEEKSFORGEEKS'``B ``=` `'GEEKSFORGEEKG'` `if` `(canBeEqual(A, B, ``len``(A))):``    ``print``(``"Yes"``)``else``:``    ``print``(``"No"``)`

## C#

 `// C# implementation of the above approach``using` `System;``using` `System.Collections.Generic;` `class` `GFG``{``    ` `// Function that returns true if the string``// can be made equal after one swap``static` `Boolean canBeEqual(``char` `[]a,``                          ``char` `[]b, ``int` `n)``{``    ``// A and B are new a and b``    ``// after we omit the same elements``    ``List<``char``> A = ``new` `List<``char``>();``    ``List<``char``> B = ``new` `List<``char``>();` `    ``// Take only the characters which are``    ``// different in both the strings``    ``// for every pair of indices``    ``for` `(``int` `i = 0; i < n; i++)``    ``{` `        ``// If the current characters differ``        ``if` `(a[i] != b[i])``        ``{``            ``A.Add(a[i]);``            ``B.Add(b[i]);``        ``}``    ``}``    ` `    ``// The strings were already equal``    ``if` `(A.Count == B.Count &&``        ``B.Count == 0)``        ``return` `true``;` `    ``// If the lengths of the``    ``// strings are two``    ``if` `(A.Count == B.Count &&``        ``B.Count == 2)``    ``{` `        ``// If swapping these characters``        ``// can make the strings equal``        ``if` `(A == A &&``            ``B == B)``            ``return` `true``;``    ``}``    ``return` `false``;``}` `// Driver code``public` `static` `void` `Main(String[] args)``{``    ``char` `[]A = ``"SEEKSFORGEEKS"``.ToCharArray();``    ``char` `[]B = ``"GEEKSFORGEEKG"``.ToCharArray();``    ` `    ``if` `(canBeEqual(A, B, A.Length))``        ``Console.WriteLine(``"Yes"``);``    ``else``        ``Console.WriteLine(``"No"``);``}``}` `// This code is contributed by PrinciRaj1992`

## Javascript

 ``
Output:
`Yes`

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