1347. Minimum Number of Steps to Make Two Strings Anagram.cpp

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.










// Using hash table

class Solution {
public:
    int minSteps(string s, string t) {
        int slen=s.length();
        int tlen=t.length();

        vector<int> freq(26, 0);

        for(int i=0;i<slen;i++) freq[s[i]-'a']++;

        int cnt=0;

        for(int i=0;i<tlen;i++){
            if(freq[t[i]-'a']<=0){
                cnt++;
            } else freq[t[i]-'a']--;
        }

        return cnt;

    }
};