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） 
*/