524. Longest Word in Dictionary through Deleting

Given a string and a string dictionary, find the longest string in the dictionary that can be formed by deleting some characters of the given string. If there are more than one possible results, return the longest word with the smallest lexicographical order. If there is no possible result, return the empty string.

Example 1:

Input:s = "abpcplea", d = ["ale","apple","monkey","plea"]Output: "apple"

Example 2:

Input:s = "abpcplea", d = ["a","b","c"]Output: "a"

Note:

1. All the strings in the input will only contain lower-case letters.
2. The size of the dictionary won't exceed 1,000.
3. The length of all the strings in the input won't exceed 1,000.

本来以为是用LCS的，结果TLE了

原来只用判断

是否公共最长子序列是要比较的那个短字符串即可。

用两个“指针”挨个后移比较即可。

class Solution {public:    string findLongestWord(string s, vector<string>& d) {        string res = "";        for(auto &str : d){            int l = ls(str, s);            //cout << l << endl;            if (l == str.size()){                if (str.size() > res.size())                    res = str;                else if (str.size() == res.size() && str < res)                    res = str;            }        }        return res;    }    int ls(const string &s1, const string &s2){        if (s1.size() == 0 || s2.size() == 0)            return 0;        int i = 0, j = 0;        while(i < s1.size()){            while(j < s2.size() && s1[i] != s2[j])                j++;            if (j == s2.size())                return 0;            i++;            j++;        }        return s1.size();    }};