leetcode-208. Implement Trie (Prefix Tree)

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myan991

最新推荐文章于 2024-03-22 00:51:13 发布

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本文介绍了一个Trie树（前缀树）的C++实现，包括插入、搜索和判断是否存在以给定字符串为前缀的单词等功能。适用于需要高效处理字符串匹配问题的应用场景。

leetcode-208. Implement Trie (Prefix Tree)

Implement a trie with insert, search, and startsWith methods.

Note:
You may assume that all inputs are consist of lowercase letters a-z.

class TrieNode{
public:
    TrieNode *child[26];
    bool isWord;
    TrieNode():isWord(false){
        for(auto &a: child)
            a = NULL;
    }
};   //Don't forget ;

class Trie {
public:     //Don't forget :
    /** Initialize your data structure here. */
    Trie() {
        root = new TrieNode();
    }

    /** Inserts a word into the trie. */
    void insert(string word) {
        TrieNode *p = root;
        for(auto &a : word){     //& is reference, will change the element in the string
            int i = a - 'a';
            if(!p->child[i])
                p->child[i] = new TrieNode;
            p = p->child[i];
        }
        p -> isWord = 1;
    }

    /** Returns if the word is in the trie. */
    bool search(string word) {
         TrieNode *p = root;
         for(auto &a : word){
             int i = a - 'a';
             if(!p->child[i])
                return false;
             p = p->child[i];
         }
         return p->isWord;
    }

    /** Returns if there is any word in the trie that starts with the given prefix. */
    bool startsWith(string prefix) {
        TrieNode *p = root;
        for(auto &a: prefix){
            int i = a -'a';
            if(!p -> child[i])
                return false;
            p = p->child[i];
        }
        return true;
    }
private:
    TrieNode* root;
};

/**
 * 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);
 */