HDU 1251(trie树)

统计难题

Time Limit: 4000/2000 MS (Java/Others)    Memory Limit: 131070/65535 K (Java/Others)
Total Submission(s): 10201    Accepted Submission(s): 4156

Problem Description

Ignatius最近遇到一个难题,老师交给他很多单词(只有小写字母组成,不会有重复的单词出现),现在老师要他统计出以某个字符串为前缀的单词数量(单词本身也是自己的前缀).

 

 

Input

输入数据的第一部分是一张单词表,每行一个单词,单词的长度不超过10,它们代表的是老师交给Ignatius统计的单词,一个空行代表单词表的结束.第二部分是一连串的提问,每行一个提问,每个提问都是一个字符串.

注意:本题只有一组测试数据,处理到文件结束.

 

 

Output

对于每个提问,给出以该字符串为前缀的单词的数量.

 

 

Sample Input

banana band bee absolute acm ba b band abc

 

 

Sample Output

2 3 1 0

#include <stdio.h>   

#include <string.h> 

#include <malloc.h>

#include <stdlib.h>  

const int N = 26;   

typedef struct Node    

{   

    int cnt;   

    Node *child[26];    

}Node; 

Node *root;    

void init()

{//对根节点初始化，根节点不存储任何数据

    root =(Node *)malloc(sizeof(Node)); 

    for(int i = 0; i < N; i++)

        root->child[i] = NULL;

    root->cnt = 0; 

} 

void insert(char *str)

{

    Node *current, *newnode;   

    int i, j,index;

    int len = strlen(str);    

    if(len == 0)

        return;//无须插入的情况

    current = root;

    for(i = 0; i < len; i++)

    {

        index = str[i]-'a';

        if(current->child[index]!=NULL)

        {//子树存在

            current = current->child[index];

            current->cnt++; 

        } 

        else

        {//子树不存在的情况 

            newnode =(Node *)malloc(sizeof(Node)); 

            for(j = 0; j < N; j++)

                newnode->child[j] = NULL;

            newnode->cnt = 1;            

            current->child[index] = newnode;//这一句不可少 

            current = newnode; //current = current->child[index]

        }

    }

}

int search( char *str )   

{ 

    int i, j, k, index;  

    Node *current, *newnode;    

    current = root;   

    for(i=0;str[i]!= '\0';++i )   

    {   

        index=str[i]-'a';   

        if(current->child[index]==NULL)   

            return 0;   

        current=current->child[index];   

    }         

    return current->cnt;   

}                  

int main()   

{   

    char str[15]; 

    init();  

    while(gets(str),strcmp(str, ""))   

        insert( str );   

    while(gets(str)!=NULL)   

        printf( "%d\n", search(str));   

    return 0;   

}  











//还没找到错误 

#include <stdio.h>   

#include <string.h> 

#include <malloc.h>

#include <stdlib.h>     

typedef struct Node    

{   

    int cnt;   

    Node *childs[26];   

    Node() //不可再加上struct 

    { 

        cnt = 0; 

        memset(childs,NULL,sizeof(childs)); 

    }   

}Node;    

Node *current, *newnode;  

Node *root =(Node *)malloc(sizeof(Node));       

void insert(char *str)   

{   

    int i, j, k, index; 

    current=root;   

    for(i=0;str[i]!='\0';++i)   

    {   

        index = str[i]-'a';   

        if( current->childs[index]!= NULL )   

        {   

            current = current->childs[index];   

            ++(current->cnt);   

        }   

        else    

        {   

            newnode = (Node *)malloc(sizeof(Node));

            if(newnode==NULL)

                exit(-1);               

            newnode->cnt++;//等价于 newnode->cnt=1

            current->childs[index] = newnode;   

            current = current->childs[index];   

        }   

    }   

}     

int search( char *str )   

{ 

    int i, j, k, index;   

    current = root;   

    for(i=0;str[i]!= '\0';++i )   

    {   

        index=str[i]-'a';   

        if(current->childs[index]==NULL)   

            return 0;   

        current=current->childs[index];   

    }   

       

    return current->cnt;   

}                  

int main()   

{   

    char str[15];   

    while(gets(str),strcmp(str, ""))   

        insert( str );   

    while(gets(str)!=NULL)   

        printf( "%d\n", search(str));   

    return 0;   

}  

/*

单步调试过程中，程序产生一个访问异常（段违例） 

*/