LeetCode题目392. Is Subsequence

题目原址：点击打开链接 

题目描述：Given a string s and a string t, check ifs is subsequence of t.

You may assume that there is only lower case English letters in both s andt. t is potentially a very long (length ~= 500,000) string, ands 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?

我的代码：

class Solution {public:    bool isSubsequence(string s, string t) {        int l1=s.size(),l2=t.size();        if(l1==0)return true;        for(int i=0,j=0;i<l2&&j<l1;i++){            if(s[j]==t[i]){                if(j==l1-1)return true;                j++;            }        }        return false;    }};