LeetCode - Implement Trie (Prefix Tree)

最新推荐文章于 2024-03-22 00:51:13 发布

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本文介绍了一种使用C++实现的Trie树数据结构，包括插入、查找和前缀匹配等功能。Trie树能够高效地存储和检索字符串集合。

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class TrieNode {
public:
    TrieNode *child[26];
    bool isWord;
    TrieNode(): isWord(false){
        for(auto &node: child){
            node = NULL;
        }
    }
};

class Trie {
public:
    /** Initialize your data structure here. */
    Trie() {
        head = new TrieNode();
    }
    
    /** Inserts a word into the trie. */
    void insert(string word) {
        TrieNode* cur = head;
        for(char a: word){
            int pos = a-'a';
            if(!cur->child[pos]){
                cur->child[pos] = new TrieNode();
            }
            cur = cur->child[pos];
        }
        cur->isWord = true;
    }
    
    /** Returns if the word is in the trie. */
    bool search(string word) {
        TrieNode* cur = head;
        for(char a: word){
            int pos = a-'a';
            if(!cur->child[pos]){
                return false;
            }
            cur = cur->child[pos];
        }
        return cur->isWord;      
    }
    
    /** Returns if there is any word in the trie that starts with the given prefix. */
    bool startsWith(string prefix) {
        TrieNode* cur = head;
        for(char a: prefix){
            int pos = a-'a';
            if(!cur->child[pos]) return false;
            cur = cur->child[pos];
        }
        return true;
    }
    
private:
    TrieNode* head;
};

/**
 * 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);
 */