力扣_字符串11—实现前缀树（字典树、Trie树）

题目

方法

• 对于每一个节点，初始化一个长度为26的数组，用来存储对应字母子节点的地址
• 对于每一个节点，初始化一个 $bool$ 变量用来表示是否为叶子节点

代码

class Trie {
private:
    vector<Trie*> children = vector<Trie*>(26);
    bool is_end = false;
public:
    Trie() {
    }
    
    void insert(string word) {
        int n = word.size();
        Trie* node = this;
        for(int i = 0; i < n; i++){
            if(node->children[int(word[i]-'a')] == nullptr){
                node->children[int(word[i]-'a')] = new Trie();
            }
            node = node->children[int(word[i]-'a')];
        }
        node->is_end = true;
    }
    
    bool search(string word) {
        int n = word.size();
        Trie* node = this;
        for(int i = 0; i < n; i++){
            if(node->children[int(word[i]-'a')] == nullptr){
                return false;
            }
            node = node->children[int(word[i]-'a')];
        }
        return node->is_end;
    }
    
    bool startsWith(string prefix) {
        int n = prefix.size();
        Trie* node = this;
        for(int i = 0; i < n; i++){
            if(node->children[int(prefix[i]-'a')] == nullptr){
                return false;
            }
            node = node->children[int(prefix[i]-'a')];
        }
        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);
 */