Trie实现

#include<iostream>
#include<string>
#include<algorithm>
using namespace std;
class Node{
    public:
        Node *next[26];
        bool isend;
        Node(){
            for(int i=0;i<26;i++){
                next[i]=NULL;
            }
            isend=false;
        }
        ~Node(){}
    };
class Trie {
public:
    /** Initialize your data structure here. */
    Node *root;
    Trie() {
        root=new Node();
    }

    /** insts a word into the trie. */
    void inst(string word) {
        Node *p=root;
        for(int i=0;i<word.size();i++){
            if(!p->next[word[i]-‘a‘])
                p->next[word[i]-‘a‘]=new Node();
            p=p->next[word[i]-‘a‘];
        }
        p->isend=true;
    }

    /** Returns if the word is in the trie. */
    bool se(string word) {
        Node *p=root;
        for(int i=0;i<word.size();i++){
            if(!p->next[word[i]-‘a‘])
                return false;
            p=p->next[word[i]-‘a‘];
        }
        return p->isend;
    }

    /** Returns if there is any word in the trie that starts with the given prefix. */
    bool startsWith(string prefix) {
        Node *p=root;
        for(int i=0;i<prefix.size();i++){
            if(!p->next[prefix[i]-‘a‘])
                return false;
            p=p->next[prefix[i]-‘a‘];
        }
        return true;
    }
};
int main(void){
    Trie *trie=new Trie();
    trie->inst("apple");
    cout<<trie->se("apple")<<‘ ‘;   // 返回 true
    cout<<trie->se("app")<<‘ ‘;     // 返回 false
    cout<<trie->startsWith("app")<<‘ ‘; // 返回 true
    trie->inst("app");
    cout<<trie->se("app")<<‘ ‘;     // 返回 true
    return 0;

}
/**
 * Your Trie object will be instantiated and called as such:
 * Trie* obj = new Trie();
 * obj->inst(word);
 * bool param_2 = obj->se(word);
 * bool param_3 = obj->startsWith(prefix);
 */