LeetCode208(2021.4.14)

LC208. 实现 Trie (前缀树)

class Trie {
private:
    vector<Trie *> children;
    bool isEnd;

    Trie *searchPrefix(string prefix) {
        Trie *node = this;
        for (char ch : prefix) {
            ch -= 'a';
            if (node->children[ch] == nullptr) {
                return nullptr;
            }
            node = node->children[ch];
        }
        return node;
    }

public:
    Trie() : children(26), isEnd(false) {}

    void insert(string word) {
        Trie *node = this;
        for (char ch : word) {
            ch -= 'a';
            if (node->children[ch] == nullptr) {
                node->children[ch] = new Trie();
            }
            node = node->children[ch];
        }
        node->isEnd = true;
    }

    bool search(string word) {
        Trie *node = this->searchPrefix(word);
        return node != nullptr && node->isEnd;
    }

    bool startsWith(string prefix) {
        return this->searchPrefix(prefix) != nullptr;
    }
};

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