2486. Append Characters to String to Make Subsequence

You are given two strings s and t consisting of only lowercase English letters.

Return the minimum number of characters that need to be appended to the end of s so that t becomes a subsequence of s.

A subsequence is a string that can be derived from another string by deleting some or no characters without changing the order of the remaining characters.

class Solution {
public:
    int appendCharacters(string s, string t) {
        int i = 0, j = 0;
        for(; i < s.length() and j < t.length(); i++) {
            if(s[i] == t[j]) j++;
        }
        return t.length() - j;
    }
};