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LeetCode 524. Longest Word in Dictionary through Deleting

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题目

原题在此

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

Example 1:
Input: s = "abpcplea", dictionary = ["ale","apple","monkey","plea"]
Output: "apple"

Example 2:

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

Constraints:

  • 1 <= s.length<= 1000
  • 1 <= dictionary.length <= 1000
  • 1 <= dictionary[i].length <= 1000
  • s and dictionary[i] consist of lowercase English letters.

解析

根据题意, 将字典按照先长度后字典序的规则排序, 然后逐一比对s中是否包含字典元素的子序列即可.

代码

c++

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#pragma GCC optimize("Ofast")
static auto speedup = [](){
    std::ios::sync_with_stdio(false);
    std::cin.tie(nullptr);
    std::cout.tie(nullptr);
    return nullptr;
}();

class Solution {
public:    
    string findLongestWord(string s, vector<string>& d) {
        auto cmp = [](string &a, string &b) {
            if(a.length() != b.length())
                return a.length() > b.length();
            return a < b;
        };
        sort(d.begin(), d.end(), cmp);
        
        for(auto word : d) {
            if(contains(s, word))
                return word;
        }
        return "";
    }

private:
    inline bool contains(string &s, string &t) {
        int n = s.length(), m = t.length();
        int i = 0 , j = 0;
        while(i < n and j < m)
            if(s[i] == t[j]) i++ , j++;
            else i++;
        return j == m;
    }
};