实现 Trie (前缀树)

Leetcode题目链接

描述

详见中文题目链接。

解答

class Trie {
private:
    const static int N = 31010;
    int son[N][26] {0};
    int cnt[N] {0};
    int idx = 0;
public:
    Trie() {

    }

    void insert(string word) {
        int p = 0;
        for (char ch : word) {
            int u = ch - 'a';
            if (!son[p][u]) son[p][u] = ++idx;
            p = son[p][u];
        }
        cnt[p]++;
    }

    bool search(string word) {
        int p = 0;
        for (char ch : word) {
            int u = ch - 'a';
            if (!son[p][u]) return false;
            p = son[p][u];
        }
        return cnt[p] > 0;
    }

    bool startsWith(string prefix) {
        int p = 0;
        for (char ch : prefix) {
            int u = ch - 'a';
            if (!son[p][u]) return false;
            p = son[p][u];
        }
        return true;
    }
};

/**
 * Your Trie object will be instantiated and called as such:
 * Trie* obj = new Trie();
 * obj->insert(word);
 * bool param_2 = obj->search(word);
 * bool param_3 = obj->startsWith(prefix);
 */