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  • [LintCode] Implement Trie 实现字典树

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

    Have you met this question in a real interview?

     
     
    Example
    Note

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

    LeetCode上的原题,请参见我之前的博客Implement Trie (Prefix Tree) 实现字典树(前缀树)

    /**
     * Your Trie object will be instantiated and called as such:
     * Trie trie;
     * trie.insert("lintcode");
     * trie.search("lint"); will return false
     * trie.startsWith("lint"); will return true
     */
    class TrieNode {
    public:
        // Initialize your data structure here.
        TrieNode *child[26];
        bool isWord;
        TrieNode(): isWord(false) {
            for (auto & a : child) a = NULL;
        }
    };
    
    class Trie {
    public:
        Trie() {
            root = new TrieNode();
        }
    
        // Inserts a word into the trie.
        void insert(string word) {
            TrieNode *p = root;
            for (auto &a : word) {
                int i = a - 'a';
                if (!p->child[i]) p->child[i] = new TrieNode();
                p = p->child[i];
            }
            p->isWord = true;
        }
    
        // 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;
    };
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  • 原文地址:https://www.cnblogs.com/grandyang/p/4868908.html
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