392.判斷子序列

題解：

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