472 Concatenated Words 连接的单词

详见：https://leetcode.com/problems/concatenated-words/description/

C++：

class Solution {
public:
    vector<string> findAllConcatenatedWordsInADict(vector<string>& words)
    {
        if (words.size() <= 2)
        {
            return {};
        }
        vector<string> res;
        unordered_set<string> dict(words.begin(), words.end());
        for (string word : words)
        {
            dict.erase(word);
            int len = word.size();
            if (len == 0)
            {
                continue;
            }
            vector<bool> v(len + 1, false);
            v[0] = true;
            for (int i = 0; i < len + 1; ++i)
            {
                for (int j = 0; j < i; ++j)
                {
                    if (v[j] && dict.count(word.substr(j, i - j)))
                    {
                        v[i] = true;
                        break;
                    }
                }
            }
            if (v.back())
            {
                res.push_back(word);
            }
            dict.insert(word);
        }
        return res;
    }
};

参考：https://www.cnblogs.com/grandyang/p/6254527.html