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"

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?

public class Solution {
    public boolean isSubsequence(String s, String t) {
        int len1=s.length();
        int len2=t.length();
        int index1=0;
        int index2=0;
        while(index1<len1&&index2<len2)
        {
           if(t.charAt(index2)==s.charAt(index1)) index1++;
           index2++;
        }
        if(index1==len1) return true;
        else return false;
    }
}