leetcode刷题系列：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 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" 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?

Credits:
Special thanks to @pbrother for adding this problem and creating all test cases.

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class Solution {public:    bool isSubsequence(string s, string t) {        int lens = s.size();        int lent = t.size();        if(lens > lent)            return false;        int start = 0;        int j = 0;        for(int i = 0; i < lens; ++i)        {            for(; j < lent;j++)            {                if(s[i] == t[j])                {                    if(j == lent - 1 && i != lens - 1)                        return false;                    j++;                    break;                }                else                {                    if(  j == lent - 1 )                        return false;                    continue;                }            }        }        return true;    }};