LeetCode题目392. Is Subsequence

最新推荐文章于 2020-05-20 11:53:52 发布

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本文介绍了一个简单的C++算法实现，用于判断一个字符串是否为另一个字符串的子序列。该算法适用于两个字符串长度相差较大且较长字符串长度可达500,000的情况。

题目原址：点击打开链接

题目描述：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?

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;
    }
};