Minimum swaps required to convert one binary string to another
Last Updated :
28 Sep, 2022
Given two binary string M and N of equal length, the task is to find a minimum number of operations (swaps) required to convert string N to M.
Examples:
Input: str1 = "1101", str2 = "1110"
Output: 1
Swap last and second last element in the binary string,
so that it become 1101
Input: str1 = "1110000", str2 = "0001101"
Output: 3
Approach:
Initialize the counter and Iterate over the M such that if any non-equal elements found in both binary strings, increment the counter. In the end, if the counter is even then print the result/2 because for one swap two elements are non-identical.
Suppose S1 = "10" and S2 = "01", so two pairs are non-identical, the count = 2 and as the count is even, so number of swaps are count/2, i.e. 1. Even count determines that there are chances to swap the elements.
Below is the implementation of the above approach:
C++
// C++ implementation of the above approach
#include <bits/stdc++.h>
using namespace std;
// Method to count swaps
void minSwaps(string str1, string str2)
{
// Initialize the count
int count = 0;
// Iterate the loop with str1 length
for (int i = 0; i < str1.length(); i++) {
// If any non-equal elements are found
// increment the counter
if (str1[i] != str2[i])
count++;
}
// If counter is even print the swap
if (count % 2 == 0)
cout << count / 2;
else
cout << "Not Possible";
}
// Driver code
int main()
{
// Take two input
string binaryString1 = "1110000";
string binaryString2 = "0001101";
// Call the method
minSwaps(binaryString1, binaryString2);
return 0;
}
// Java Program to count minimum number of swap
// required to make string N to M
public class GFG {
// Method to count swaps
static void minSwaps(String str1, String str2)
{
// Initialize the count
int count = 0;
// Iterate the loop with str1 length
for (int i = 0; i < str1.length(); i++) {
// If any non-equal elements are found
// increment the counter
if (str1.charAt(i) != str2.charAt(i))
count++;
}
// If counter is even print the swap
if (count % 2 == 0)
System.out.println(count / 2);
else
System.out.println("Not Possible");
}
// Driver Code
public static void main(String args[])
{
// Take two input
String binaryString1 = "1110000";
String binaryString2 = "0001101";
// Call the method
minSwaps(binaryString1, binaryString2);
}
}
# Python3 implementation of
# the above approach
# function to count swaps
def minSwaps(str1, str2) :
# Initialize the count
count = 0
# Iterate the loop with
# length of str1
for i in range(len(str1)) :
# If any non-equal elements are
# found increment the counter
if str1[i] != str2[i] :
count += 1
# If counter is even print
# the swap
if count % 2 == 0 :
print(count // 2)
else :
print("Not Possible")
# Driver code
if __name__ == "__main__" :
# Take two input
binaryString1 = "1110000"
binaryString2 = "0001101"
# Call the function
minSwaps( binaryString1, binaryString2)
# This code is contributed by ANKITRAI1
// C# Program to count minimum number of swap
// required to make string N to M
using System;
class GFG
{
// Method to count swaps
static void minSwaps(string str1, string str2)
{
// Initialize the count
int count = 0;
// Iterate the loop with str1 length
for (int i = 0; i < str1.Length; i++) {
// If any non-equal elements are found
// increment the counter
if (str1[i] != str2[i])
count++;
}
// If counter is even print the swap
if (count % 2 == 0)
Console.WriteLine(count / 2);
else
Console.WriteLine("Not Possible");
}
// Driver Code
public static void Main()
{
// Take two input
string binaryString1 = "1110000";
string binaryString2 = "0001101";
// Call the method
minSwaps(binaryString1, binaryString2);
}
}
// This code is contributed
// by Akanksha Rai(Abby_akku)
<?php
// PHP implementation of the above
// approach
// Method to count swaps
function minSwaps($str1, $str2)
{
// Initialize the count
$count = 0;
// Iterate the loop with str1 length
for ($i = 0; $i < strlen($str1); $i++)
{
// If any non-equal elements are
// found increment the counter
if ($str1[$i] != $str2[$i])
$count++;
}
// If counter is even print the swap
if ($count % 2 == 0)
echo ($count / 2);
else
echo "Not Possible";
}
// Driver code
// Take two input
$binaryString1 = "1110000";
$binaryString2 = "0001101";
// Call the method
minSwaps($binaryString1, $binaryString2);
// This code is contributed
// by Sach_Code
?>
<script>
// JavaScript Program to count minimum number of swap
// required to make string N to M
// Method to count swaps
function minSwaps(str1, str2) {
// Initialize the count
var count = 0;
// Iterate the loop with str1 length
for (var i = 0; i < str1.length; i++) {
// If any non-equal elements are found
// increment the counter
if (str1[i] !== str2[i]) count++;
}
// If counter is even print the swap
if (count % 2 === 0) document.write(count / 2);
else document.write("Not Possible");
}
// Driver Code
// Take two input
var binaryString1 = "1110000";
var binaryString2 = "0001101";
// Call the method
minSwaps(binaryString1, binaryString2);
</script>
Time Complexity: O(n)
Auxiliary Space: O(1) it is using constant space for variables
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