LeetCode - Is Subsequence

Given two strings s and t, check if s is a subsequence of t.

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).

 

Example 1:

Input: s = "abc", t = "ahbgdc"
Output: true
Example 2:

Input: s = "axc", t = "ahbgdc"
Output: false
 

Constraints:

0 <= s.length <= 100
0 <= t.length <= 104
s and t consist only of lowercase English letters.
 

Follow up: If there are lots of incoming s, say s1, s2, ..., sk where k >= 109, and you want to check one by one to see if t has its subsequence. In this scenario, how would you change your code?

 

class Solution {
    public boolean isSubsequence(String s, String t) {
        if (s.length() == 0) {
            return true;
        }
        if (t.length() == 0) {
            return false;
        }
        
        int i = 0;
        for (int j = 0; j < t.length(); j++) {
            if(t.charAt(j) == s.charAt(i)) {
                if(i == s.length() - 1) {
                    return true;
                }
                i++;
            }
        }
        return false;
    }
}