poj3349 Snowflake Snow Snowflakes

做的第一道hash题目，不知道什么情况该用什么方法hash

code

#include <set>
#include <map>
#include <ctime>
#include <queue>
#include <cmath>
#include <stack>
#include <limits>
#include <vector>
#include <bitset>
#include <string>
#include <cstdio>
#include <cstring>
#include <fstream>
#include <string.h>
#include <iostream>
#include <algorithm>
#define Si set<int>
#define LL long long
#define pb push_back
#define PS printf(" ")
#define Vi vector<int>
#define LN printf("\n")
#define lson l,m,rt << 1
#define rson m+1,r,rt<<1|1
#define SD(a) scanf("%d",&a)
#define PD(a) printf("%d",a)
#define SET(a,b) memset(a,b,sizeof(a))
#define FF(i,a) for(int i(0);i<(a);i++)
#define FD(i,a) for(int i(a);i>=(1);i--)
#define FOR(i,a,b) for(int i(a);i<=(b);i++)
#define FOD(i,a,b) for(int i(a);i>=(b);i--)
#define readf freopen("input.txt","r",stdin)
#define writef freopen("output.txt","w",stdout)
const int maxn = 1000002;
const long long BigP=999983;
const int INF = 0x3fffffff;
const int dx[]={0,1,0,-1};
const int dy[]={1,0,-1,0};
const double pi = acos(-1.0);
const double eps= 1e-7;
using namespace std;
//采用相加取余大素数的hash
int N;
struct node{
    bool use;
    int arm[6];
    node *next;
}snows[maxn];
void insert(int arm[],struct node *p){
    if(!(p->use)){
        FF(i,6){
            p->arm[i]=arm[i];
        }
        p->use=true;
        p->next= new node;
        p->next->use=false;
    }else{
        p=p->next;
        insert(arm,p);
    }
}
LL hash(int arm[]){
    LL t=0;
    FF(i,6){
        t=(t+arm[i]%BigP)%BigP;
    }
    return t;
}
bool cmp(int a[],int b[]){//一共六个元素，就这样好了。。。囧。。。
    if (a[0]==b[0]&&a[1]==b[1]&&a[2]==b[2]&&a[3]==b[3]&&a[4]==b[4]&&a[5]==b[5])      return 1;
    else if(a[0]==b[1]&&a[1]==b[2]&&a[2]==b[3]&&a[3]==b[4]&&a[4]==b[5]&&a[5]==b[0])  return 1;
    else if(a[0]==b[2]&&a[1]==b[3]&&a[2]==b[4]&&a[3]==b[5]&&a[4]==b[0]&&a[5]==b[1])  return 1;
    else if(a[0]==b[3]&&a[1]==b[4]&&a[2]==b[5]&&a[3]==b[0]&&a[4]==b[1]&&a[5]==b[2])  return 1;
    else if(a[0]==b[4]&&a[1]==b[5]&&a[2]==b[0]&&a[3]==b[1]&&a[4]==b[2]&&a[5]==b[3])  return 1;
    else if(a[0]==b[5]&&a[1]==b[0]&&a[2]==b[1]&&a[3]==b[2]&&a[4]==b[3]&&a[5]==b[4])  return 1;
    else return 0;
}
bool search(int arm[],struct node *p){
    int arm2[6];
    FF(i,6){
        arm2[i]=arm[5-i];
    }

    while(p->use){
        int tmp[6];
        FF(i,6) tmp[i]=p->arm[i];
        if( cmp(tmp,arm) || cmp(tmp,arm2) ) return true;
        p=p->next;
    }
    return false;
}
void init(node a){
    a.use=false;
    a.next=NULL;
}
int main()
{
    SD(N);
    FOR(i,0,999983){
        init(snows[i]);
    }
    int arm[6];
    FOR(i,1,N){
        FF(i,6) SD(arm[i]);
        LL k=hash(arm);
        struct node *p=&snows[k];
        if( !search(arm,p) ) insert(arm,p);
        else{
            printf("Twin snowflakes found.\n");
            return 0;
        }
    }
    printf("No two snowflakes are alike.\n");
    return 0;
}