pku 2503 Babelfish 哈希

http://poj.org/problem?id=2503

很简单的一个哈希，本来想求和然后模一个数哈希呢，提交果断tle。。。郁闷。最后看了看别人的哈希,在处理的时候好像用到了经典的unix的ELF哈希函数给输入字符串生产哈希值.我直接套的这个函数，提交就A了。。。

unix的ELF哈希函数

View Code

unsigned int ELFHash(char* str)
{
    unsigned int hash = 0;
    unsigned int x = 0;

    while (*str){
        hash = (hash << 4) + (*str++);
        if ((x = hash & 0xF0000000L) != 0){
            hash ^= (x >> 24);
            hash &= ~x;
        }
    }
    return (hash & 0x7FFFFFFF);
}

View Code

#include <iostream>
#include <cstring>
#include <cstdio>
#define maxn 100007
using namespace std;

struct node
{
    char str1[12];
    char str2[12];
    node *next;
}*p[maxn],H[maxn];
int pos;

unsigned int ELFHash(char* str)
{
    unsigned int hash = 0;
    unsigned int x = 0;

    while (*str){
        hash = (hash << 4) + (*str++);
        if ((x = hash & 0xF0000000L) != 0){
            hash ^= (x >> 24);
            hash &= ~x;
        }
    }
    return (hash & 0x7FFFFFFF);
}
int main()
{
    int i,tmp;
    char s1[12],s2[12];
    char s[24];
    pos = 0;
    memset(p,0,sizeof(p));
    while (gets(s) != NULL && s[0] != '\0')
    {
        tmp = 0;
        int len = strlen(s);
        for (i = 0; i < len; ++i)
        {
            if (s[i] != ' ')
            s1[i] = s[i];
            else
            break;
        }
        s1[i++] = '\0';
        int k = 0;
        for (; i < len; ++i)
        s2[k++] = s[i];
        s2[k] = '\0';
        tmp = ELFHash(s2)%maxn;
        node *t = &H[pos++];
        strcpy(t->str1,s1);
        strcpy(t->str2,s2);
        t->next = p[tmp];
        p[tmp] = t;
    }
    while (~scanf("%s",s1))
    {
         tmp = 0;
        tmp = ELFHash(s1)%maxn;
       node *q; bool flag = false;
       for (q = p[tmp]; q != NULL; q = q->next)
       {
           if (!strcmp(q->str2,s1))
           {
               printf("%s\n",q->str1);
               flag = true;
               break;
           }
       }
       if (!flag) printf("eh\n");
    }
    return 0;
}