ACM: hash题 poj 2503

最新推荐文章于 2022-04-14 20:17:20 发布

Smile_Benson

最新推荐文章于 2022-04-14 20:17:20 发布

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这篇博客介绍了如何使用哈希数据结构解决POJ 2503题目的翻译问题。首先读取字典建立哈希表，然后通过哈希函数快速查找并翻译输入的外文单词，未找到的单词翻译为'eh'。示例代码展示了具体的实现过程。

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Babelfish

Description

You have just moved from Waterloo to a big city. The people here speak an incomprehensible dialect of a foreign language. Fortunately, you have a dictionary to help you understand them.

Input

Input consists of up to 100,000 dictionary entries, followed by a blank line, followed by a message of up to 100,000 words. Each dictionary entry is a line containing an English word, followed by a space and a foreign language word. No foreign word appears more than once in the dictionary. The message is a sequence of words in the foreign language, one word on each line. Each word in the input is a sequence of at most 10 lowercase letters.

Output

Output is the message translated to English, one word per line. Foreign words not in the dictionary should be translated as "eh".

Sample Input

dog ogday

cat atcay

pig igpay

froot ootfray

loops oopslay

atcay

ittenkay

oopslay

Sample Output

cat

loops

题意: 翻译

解题思路:

1. hash开散列求解

代码:

#include <cstdio>
#include <iostream>
#include <cstring>
using namespace std;
#define MAX 100005
#define MAXHASH 99983

struct node
{
   char english[100];
   char other[100];
   node *next;
}hash[MAX];

int num;

int elfHash(char *key)
{
   unsigned long h = 0;
   while(*key)
   {
       h = (h << 4) + *key++;
       unsigned long g = h & 0xf0000000L;
       if(g) h ^= g >> 24;
       h &= ~g;
   }
   return (h+MAXHASH) % MAXHASH;
}

void read_dictionary()
{
   memset(hash,NULL,sizeof(hash));
   char ch;

   while(true)
   {
       ch = getchar();

       if(ch == '\n')
           break;

       char str1[100];
       char str2[100];
       str1[0] = ch;
       scanf("%s %s",str1+1,str2);
       ch = getchar();
//       printf("%s %s\n",str1,str2);
       int k = elfHash(str2);

       node *p,*q;
       for(p = q = &hash[k]; p != NULL; q = p, p = p->next);
       node *newOne = new node;
       strcpy(newOne->english,str1);
       strcpy(newOne->other,str2);
       q->next = newOne;
       newOne->next = NULL;
   }
}

void find(char *str)
{
   int k = elfHash(str);
   node *p;
   for(p = &hash[k]; p != NULL; p = p->next)
   {
       if(strcmp(p->other,str) == 0)
           break;
   }
   if(p == NULL)
       printf("eh\n");
   else
       printf("%s\n",p->english);
}

int main()
{
//   freopen("input.txt","r",stdin);
   char str[100];
   read_dictionary();
   while(scanf("%s",str) != EOF)
   {
       find(str);
   }
   return 0;
}