字典树模板

把数据都存在一个TrieNode数组里，只保存其指向关系。

class TrieNode {
public:
    bool end;
    vector<int> son;
    TrieNode() {
        end = false;
        son = vector<int>(26, -1);
    }
};

class Trie {
public:
    vector<TrieNode> tree;

    Trie() {
        tree.push_back(TrieNode());
    }

    bool query(string& s) {
        int idx = 0;
        for(char c : s) {
            int to = tree[idx].son[c - 'a'];
            if (to == -1) return false;
            idx = to;
        }
        return tree[idx].end;
    }

    void insert(string &s) {
        int idx = 0;
        for (char c : s) {
            if (tree[idx].son[c - 'a'] == -1) {
                tree[idx].son[c - 'a'] = tree.size();
                tree.push_back(TrieNode());
            }
            idx = tree[idx].son[c - 'a'];
        }
        tree[idx].end = true;
    }
};