POJ 3349 Snowflake Snow Snowflakes

简单hash

#include<stdio.h>
#include<stdlib.h>;
#include<algorithm>
#define inf 100001
using namespace std; 
struct Edge{
	int a[10],next;
}edge[100100];
int a[10],head[100100],cnt;
bool add(int * b){
	int sum=0,i,j,p,q;
	for(i=0;i<6;i++)
		sum+=b[i];
	int hash=sum%inf;
	for(i=head[hash];i;i=edge[i].next){
		for(j=0;j<6;j++){
			if(edge[i].a[j]==b[0]){
				for(p=0,q=j;p<6;p++){
					if(b[p]!=edge[i].a[q])
						break;
						q=(q+1)%6;
				}
				if(p==6)return 1;
				for(p=0,q=j;p<6;p++){
					if(b[p]!=edge[i].a[q])
						break;
					q=(q-1+6)%6;
				}
				if(p==6)return 1;
			}
		}
	}
	++cnt;
	for(i=0;i<6;i++)
		edge[cnt].a[i]=b[i];
	edge[cnt].next=head[hash];
	head[hash]=cnt;
	return 0;
}
int main(){
	int i,j,n;
	scanf("%d",&n);
	bool flag=0;
	for(i=1;i<=n;i++){
		for(j=0;j<6;j++){
			scanf("%d",&a[j]);
		}
		if(flag)continue;
		if(add(a))flag=1;
	}
	if(flag)            
		printf("Twin snowflakes found.\n");        
	else            
		printf("No two snowflakes are alike.\n");
}