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  • 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.

    Approach #1:

    class Solution {
    public:
        bool isSubsequence(string s, string t) {
            int len1 = s.length();
            int len2 = t.length();
            if (len1 == 0) return true;
            queue<char> q;
            for (int i = 0; i < len1; ++i) {
                q.push(s[i]);
            }
            for (int i = 0; i < len2; ++i) {
                if (q.front() == t[i]) {
                    q.pop();
                }
                if (q.empty()) return true;
            }
            return false;
        }
    };
    
    Runtime: 52 ms, faster than 64.57% of C++ online submissions for Is Subsequence.
    永远渴望,大智若愚(stay hungry, stay foolish)
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  • 原文地址:https://www.cnblogs.com/h-hkai/p/9910106.html
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