392_Is_Subsequence.java

//
// Given a string s and a string t, check if s is subsequence of t.
//
//
//
// You may assume that there is only lower case English letters in both s and t. t is potentially a very long (length ~= 500,000) string, and s is a short string (<=100).
//
//
//
// 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).
//
//
// Example 1:
// s = "abc", t = "ahbgdc"
//
//
// Return true.
//
//
// Example 2:
// s = "axc", t = "ahbgdc"
//
//
// Return false.
//
//
// 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.


class Solution {
    public boolean isSubsequence(String s, String t) {
        int i=0;
        int j=0;
        while(i<s.length()&&j<t.length()){
            if(s.charAt(i)==t.charAt(j)){
                i++;
                j++;
            }else{
                j++;
            }
        }
        return i==s.length();
    }
}