392. Is Subsequence.cpp

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

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

Follow up:
If there are lots of incoming S, say S1, S2, ... , Sk where k >= 1B, 
and you want to check one by one to see if T has its subsequence. 
In this scenario, how would you change your code?

Credits:
Special thanks to @pbrother for adding this problem and creating all test cases.



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 <= 10^4
Both strings consists only of lowercase characters.









TC -> O(N)
SC -> O(1)

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