Formatted question description: https://leetcode.ca/all/1347.html

1347. Minimum Number of Steps to Make Two Strings Anagram (Medium)

Given two equal-size strings s and t. In one step you can choose any character of t and replace it with another character.

Return the minimum number of steps to make t an anagram of s.

An Anagram of a string is a string that contains the same characters with a different (or the same) ordering.

 

Example 1:

Input: s = "bab", t = "aba"
Output: 1
Explanation: Replace the first 'a' in t with b, t = "bba" which is anagram of s.

Example 2:

Input: s = "leetcode", t = "practice"
Output: 5
Explanation: Replace 'p', 'r', 'a', 'i' and 'c' from t with proper characters to make t anagram of s.

Example 3:

Input: s = "anagram", t = "mangaar"
Output: 0
Explanation: "anagram" and "mangaar" are anagrams. 

Example 4:

Input: s = "xxyyzz", t = "xxyyzz"
Output: 0

Example 5:

Input: s = "friend", t = "family"
Output: 4

 

Constraints:

• 1 <= s.length <= 50000
• s.length == t.length
• s and t contain lower-case English letters only.

Related Topics:
String

Solution 1.

// OJ: https://leetcode.com/problems/minimum-number-of-steps-to-make-two-strings-anagram/

// Time: O(N)
// Space: O(1)
class Solution {
public:
    int minSteps(string s, string t) {
        int cnt[26] = {0}, ans = 0;
        for (char c : s) cnt[c - 'a']++;
        for (char c : t) cnt[c - 'a']--;
        for (int n : cnt) {
            if (n > 0) ans += n;
        }
        return ans;
    }
};

Java

class Solution {
    public int minSteps(String s, String t) {
        int length = s.length();
        int[] counts = new int[26];
        for (int i = 0; i < length; i++) {
            char c1 = s.charAt(i), c2 = t.charAt(i);
            counts[c1 - 'a']++;
            counts[c2 - 'a']--;
        }
        int steps = 0;
        for (int i = 0; i < 26; i++) {
            if (counts[i] > 0)
                steps += counts[i];
        }
        return steps;
    }
}

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