Find Minimum Number of Steps to Make Two Strings Anagram II

Given two strings S and T, the task is to find the minimum number of steps to make S and T anagrams of each other. In one step, we can append any character to either S or T.

Example:

Input: S = "gee", T = "eks"
Output: 4
Explanation: Append 'k' and 's' to string S and append 'g' and 'e' to string T to make S and T anagram of each other.

Input: S = "geeks", T = "egesk"
Output: 0
Explanation: "geeks" and "egesk" are anagrams.

Approach: To solve the problem, follow the below idea:

To solve this problem, the idea is to count the frequency of each character in both strings S and T. Then, calculate the difference in frequencies for each character. The sum of positive differences will give the minimum number of steps needed to make T an anagram of S.

Step-by-step algorithm:

• Count the frequency of each character in both strings S and T.
• For each character, calculate the difference in frequency between S and T.
• Sum the positive differences to get the minimum number of steps required.

Below is the implementation of the algorithm:

#include <bits/stdc++.h>
using namespace std;

// Function to find minimum steps to make S and T anagram of
// each other
int minSteps(string S, string T)
{
    // Frequency array to store the difference between
    // frequency of characters
    int freq[26] = {};
    // For every character in S, add 1 to the frequency
    // array
    for (char ch : S) {
        freq[ch - 'a'] += 1;
    }
    // For every character in S, subtract 1 to the frequency
    // array
    for (char ch : T) {
        freq[ch - 'a'] -= 1;
    }
    // Sum of absolute difference is the required number of
    // steps
    int ans = 0;
    for (int i = 0; i < 26; i++) {
        ans += abs(freq[i]);
    }
    return ans;
}

int main()
{
    // Sample Input
    string S = "gee";
    string T = "eks";
    cout << minSteps(S, T) << endl;

    return 0;
}

import java.util.*;

public class MinStepsAnagram {

    // Function to find minimum steps to make S and T
    // anagram of each other
    public static int minSteps(String S, String T)
    {
        // Frequency array to store the difference between
        // frequency of characters
        int[] freq = new int[26];

        // For every character in S, add 1 to the frequency
        // array
        for (char ch : S.toCharArray()) {
            freq[ch - 'a'] += 1;
        }

        // For every character in T, subtract 1 from the
        // frequency array
        for (char ch : T.toCharArray()) {
            freq[ch - 'a'] -= 1;
        }

        // Sum of absolute differences is the required
        // number of steps
        int ans = 0;
        for (int i = 0; i < 26; i++) {
            ans += Math.abs(freq[i]);
        }

        return ans;
    }

    public static void main(String[] args)
    {
        // Sample Input
        String S = "gee";
        String T = "eks";
        System.out.println(minSteps(S, T));
    }
}

// This code is contributed by Shivam Gupta

4

Time Complexity: O(n), where n is the length of the strings S and T.
Auxiliary Space: O(1), since the size of the frequency arrays is constant (26 for each alphabet letter).