problem

题意：

solution1: BFS;

class Solution {public:    string longestWord(vector
     
      & words) {        string res = "";        unordered_set
      
        s(words.begin(), words.end());        queue
       
         q;        for(auto word:words)        {            if(word.size()==1) q.push(word);        }        int maxLen = 0;        while(!q.empty())        {            string t = q.front();            q.pop();            if(t.size()>maxLen)             {                maxLen = t.size();                res = t;//err....            }            else if(t.size()==maxLen) res = min(res, t);            for(char ch='a'; ch<='z'; ++ch)//err...            {                t.push_back(ch);                if(s.count(t)) q.push(t);                t.pop_back();            }        }        return res;    }};
       
      
     

solution2:

class Solution {public:    string longestWord(vector
     
      & words) {        string res = "";        unordered_set
      
        s(words.begin(), words.end());        int maxLen = 0;        for (auto word:words)        {            if(word.size()==1) helper(s, word, maxLen, res);        }        return res;    }    void helper(unordered_set
       
        & s, string word, int& maxLen, string& res) {        if(word.size()>maxLen)        {            maxLen = word.size();            res = word;        }        else if(word.size()==maxLen) res = min(res, word);        for(char ch = 'a'; ch<='z'; ++ch)        {            word.push_back(ch);            if(s.count(word)) helper(s, word, maxLen, res);            word.pop_back();        }    }};
       
      
     

 

参考

1. ;

2. ;

完