392. Is Subsequence

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 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?

检验字符串s是否是字符串t的子串。

代码：

class Solution {public:bool isSubsequence(string s, string t){if(s.empty()) return true;int i = 0, l = s.size();for(auto& c:t){if(s[i] == c){++i;}if(i == l){return true;}}return false;}};