class Solution {
    public boolean isSubsequence(String s, String t) {
        if(s.length()==0) return true;
        int is=0, it=0;
        while(it<t.length()){
            if(s.charAt(is)==t.charAt(it)){
                is++;
                if(is==s.length()) return true;
            }
            it++;
        }
        return false;
    }
}