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

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” 

 After removing  the elements which are the same and have the same index in both the strings. We have string A=”SS” and B=”GG”.

The new strings are of length two and both the elements in each string are same.Hence swapping is possible.
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 <bits/stdc++.h>
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[0] == A[1] and B[0] == B[1])
            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<Character> A = new Vector<>();
    Vector<Character> 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[0] == A[1] &&
            B[0] == B[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))
        Console.WriteLine("Yes");
    else
        Console.WriteLine("No");
}
}

// This code is contributed by PrinciRaj1992

Javascript

<script>
// Javascript implementation of the approach

// Function that returns true if the string
// can be made equal after one swap
function canBeEqual(a,b,n)
{
    // A and B are new a and b
    // after we omit the same elements
    let A = [];
    let B = [];

    // Take only the characters which are
    // different in both the strings
    // for every pair of indices
    for (let i = 0; i < n; i++)
    {

        // If the current characters differ
        if (a[i] != b[i])
        {
            A.push(a[i]);
            B.push(b[i]);
        }
    }

    // The strings were already equal
    if (A.length == B.length &&
        B.length == 0)
        return true;

    // If the lengths of the
    // strings are two
    if (A.length == B.length &&
        B.length == 2)
    {

        // If swapping these characters
        // can make the strings equal
        if (A[0] == A[1] &&
            B[0] == B[1])
            return true;
    }
    return false;
}
// Driver code
let A = "SEEKSFORGEEKS".split("");
let B = "GEEKSFORGEEKG".split("");

if (canBeEqual(A, B, A.length))
    document.write("Yes");
else
    document.write("No");



// This code is contributed by unknown2108
</script>

Output:

Yes

Time Complexity: O(N), where N is the size of the given strings.

Auxiliary Space: O(N), where N is the size of the given strings.