字典树模板题（统计难题 HDU - 1251）

https://vjudge.net/problem/HDU-1251

标准的字典树模板题：

也注意一下输入方法：

#include<iostream>
#include<cstdio>
#include<cstring>
using namespace std;
const int maxn = ;
struct node
{
    int num;
    node *next[maxn];
};

//字典树
class Tree{
public:
    node *head;
    //构造函数
    Tree()
    {
        head = New();
    }
    //创建一个新节点
    node* New()
    {
        node *p = new node();
        for (int i = ; i < maxn; ++i)
        {
            p->next[i] = NULL;
        }
        p->num = ;
        return p;
    }
    //插入一个字符串
    void insert(char *str)
    {
        int len = strlen(str);
        node *t, *p = head;
        for (int i = ; i < len; ++i)
        {
            int c = str[i] - 'a';
            if (p->next[c] == NULL)
            {
                t = New();    //创建新的节点
                p->next[c] = t;
            }
                p = p->next[c];
                p->num++;
        }
    }
    int find(char *str)
    {
        node *p = head;
        int len = strlen(str);
        for (int i = ; i < len; ++i)
        {
            int c = str[i] - 'a';
            if (p->next[c] == NULL)
                return ;        //不存在这样的字符串
                p = p->next[c];
        }
        return p->num;
    }
};
int main()
{
    char s[];
    Tree tree;
    while (cin.getline(s, ))
    {
        if (strlen(s) ==  || strcmp(s, " ") == )break;    //判断是是否为空行
        tree.insert(s);
    }
    while (~scanf("%s", s))
    {
        printf("%d\n", tree.find(s));
    }
}