1251 字典树 模板

参考资料 ：

http://www.wutianqi.com/?p=1359

http://blog.youkuaiyun.com/xingyeyongheng/article/category/1516007

#include <iostream>
#include <cstdio>
#include <cstring>
#include <algorithm>
using namespace std;

struct Trie
{
    int num;
    Trie *next[26];//指针数组
}root;

void createTrie(char *str)//建树
{
    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)//对应的位置为空
        {
            q = (Trie *)malloc(sizeof(root));
            q->num = 1;
            for(int j = 0; j < 26; j++) q->next[j] = NULL;
            p->next[id] = q;
            p = p->next[id];
        }
        else
        {
            p->next[id]->num++;
            p = p->next[id];
        }
    }
}

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) return 0;
    }
    return p->num;
}

int main()
{
    char str[15];
    for(int i = 0; i < 26; i++) root.next[i] = NULL;//初始化，root 不是指针
    while(gets(str) && str[0] != '\0') createTrie(str);
    memset(str, 0, sizeof(str));
    while(scanf("%s", str) != EOF)
    {
        int ans = findTrie(str);
        printf("%d\n", ans);
    }
    return 0;
}