392. Is Subsequence

Given two strings s and t, return true if s is a subsequence of t, or false otherwise.

A subsequence of a string is a new string that is formed from the original string by deleting some (can be none) of the characters without disturbing the relative positions of the remaining characters. (i.e., “ace” is a subsequence of “abcde” while “aec” is not).

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