poj 3087 模拟（ELFHash模版，字符串哈希）

#include <iostream>
#include <cstdio>
#include <cstring>
#include <algorithm>

using namespace std;

#define MAXN 102

int N,C;
char s1[MAXN],s2[MAXN],s12[MAXN<<1],ans[MAXN<<1];

//*****************ELFhash***********
#define HASH 9901
char table[9901][MAXN];
int len;
int ELFHash(char a[MAXN])        
{
    int h = 0;
    int x  = 0;
    for(int i=0;i<len;++i)
    {
        h = (h << 4) + (a[i]);
        if ((x = h & 0xF0000000L) != 0)
        {
            h ^= (x >> 24);
            h &= ~x;
        }
    }
    return h % HASH;
}
bool is_in(char a[])    //ELFHash函数对字符串判重,没有的时候插入
{
    int i=ELFHash(a);
    while(strlen(table[i])>0&&strcmp(a,table[i])!=0)
        i=(i+1)%HASH;
    if(strlen(table[i])==0)
    {
        strcpy(table[i],a);
        return false;
    }
    return true;
}
//***********************************

int main()
{
    scanf("%d",&N);
    for(int cas=1;cas<=N;cas++)
    {
        scanf("%d",&C);getchar();
        len=C*2;
        memset(s1,0,sizeof(s1));
        memset(s2,0,sizeof(s2));
        memset(s12,0,sizeof(s12));
        memset(ans,0,sizeof(ans));
        memset(table,0,sizeof(table));
        gets(s1);
        gets(s2);
        gets(ans);
        printf("%d ",cas);
        int step=0;
        while(1)
        {
            step++;
            for(int i=0;i<len;i+=2)
                s12[i]=s2[i/2];
            for(int i=1;i<len;i+=2)
                s12[i]=s1[i/2];
            s12[len]='\0';
            //cout<<s1<<endl;
            //cout<<s2<<endl;
            if(strcmp(ans,s12)==0)
            {
                printf("%d\n",step);
                break;
            }
            else if(is_in(s12))
            {
                printf("-1\n");
                break;
            }
            for(int i=0;i<C;i++)
                s1[i]=s12[i];
            for(int i=0;i<C;i++)
                s2[i]=s12[i+C];
        }
    }
    return 0;
}