hdu 1251(字典树找前缀个数)

/*
　　 问题如题目

       典型的字典树，可以当模板
     指针的运用；
     申请空间；
*/



#include <stdio.h>
#include <string.h>
#include <stdlib.h>
struct node
{
    struct node *child[26];//指针，先申请一个地址，后面用到再申请空间
    int num;
};
struct node *root;
void insert(char *temp)
{
    struct node *cur;
    cur = root;
    int len = strlen(temp);
    for(int i =0;i < len; i++)
    {
        if(cur->child[temp[i] - 'a'] != 0){
            cur = cur->child[temp[i] - 'a'];
            cur->num ++;
        }
        else{
                struct node *newnode = new struct node ; //***
                //申请空间 == newnode=(struct node *)malloc(sizeof(struct node));   

                cur->child[temp[i] - 'a'] = newnode;
                for(int j =0;j < 26; j++){
                    newnode->child[j] = 0;
                }
                newnode->num = 1;
                cur = newnode;
        }

    }
}

int find(char *temp)
{
    struct node *cur;
    cur = root;
    int len = strlen(temp);
    if(!len) return 0;          //***
    for(int i =0;i < len; i++)
    {
        if(cur->child[temp[i] - 'a']){
            cur = cur->child[temp[i] - 'a'];
        }
        else
            return 0;
    }
    return cur->num;
}


int main()
{
    int i,j,n,len;
    char temp[20];
    root=(struct node *)malloc(sizeof(struct node));   
    for(i =0;i < 26; i++)  
        root->child[i] = 0;

    while(gets(temp) && strcmp(temp,"")!=0)
    {
        insert(temp);        
    }
    while(scanf("%s",temp)!=EOF)
    {
        printf("%d\n",find(temp));
    }
    return 0;
}