trie树（字典树）模板

#include<iostream>
#include<string.h>
using namespace std;

const int MAX=26;
struct Trie
{
    Trie *next[MAX];
    int v;   //根据需要变化,1代表无此单词，-1代表有此单词
};
Trie *root=new Trie;

void createTrie(char *str)
{
    int len = strlen(str);
    Trie *p = root, *q;
    for(int i=0; i<len; ++i)
    {
        int id = str[i]-‘a‘;
        if(p->next[id] == NULL)
        {
            // q = (Trie *)malloc(sizeof(Trie));
            q = new Trie;
            q->v = 1;    //初始v==1
            for(int j=0; j<MAX; ++j)
                q->next[j] = NULL;
            p->next[id] = q;
        }
        p = p->next[id];
    }
    p->v = -1;   //若为结尾，则将v改成-1表示
}
int findTrie(char *str)
{
    int len = strlen(str);
    Trie *p = root;
    for(int i=0; i<len; ++i)
    {
        int id = str[i]-‘a‘;
        p = p->next[id];
        if(p == NULL)   //若为空集，表示不存以此为前缀的串
            return 0;
        if(p->v == -1)   //字符集中已有串是此串的前缀
            return 1;
    }
    return 2;   //此串是字符集中某串的前缀
}
int deleteTrie(Trie* T)
{
    int i;
    if(T==NULL)
        return 0;
    for(i=0; i<MAX; i++)
    {
        if(T->next[i]!=NULL)
            deleteTrie(T->next[i]);
    }
    //free(T);
    delete(T);
    return 0;
}
int main()
{
    char str[20];
    int i;
    for(i=0; i<MAX; i++)
        root->next[i]=NULL;

    cout<<"输入串1：";
    cin>>str;
    createTrie(str);
    cout<<"输入串2：";
    cin>>str;
    cout<<findTrie(str)<<endl;
    return 0;
}