Subsequnce.java

/*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).

 

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: Suppose 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()>t.length())
        {
            return false;
        }
        int sp=0;
        int tp=0;
        while(tp<t.length())
        {
            if(sp == s.length()) return true;
            if(s.charAt(sp)==t.charAt(tp))
            {
                sp++;
            }
            tp++;
        
        }
        return sp==s.length();

        
    }
}

//tc=o(n)
//sc=o(1)