poj 3349Snowflake Snow Snowflakes

Posted 2021-01-29 dream-runner

裸的hash。

#include<iostream>
#include<cstring>
#include<algorithm>
using namespace std;
const int MOD=9999991,N=100005;
struct edge{
    int sum[7],next;
}e[N+5];
int head[N+5],cnt=0,a[7];
inline int ha(){
    int t1=0,t2=1;
    for(int i=0;i<6;++i)t1=(t1+a[i])%MOD,t2=(long long)t2*a[i]%MOD;
    return (t1+t2)%MOD;
}
inline void ins(int k){
    e[++cnt].next=head[k];memcpy(e[cnt].sum,a,sizeof(a));head[k]=cnt;
}
bool equal(int *a,int *b){
    for(register int i=0;i<6;++i){
        for(register int j=0;j<6;++j){
            int k;
            for(k=0;k<6;++k){
                if(a[(i+k)%6]!=b[(j+k)%6])break;
            }
            if(k==6)return 1;
            for(k=0;k<6;++k){
                if(a[(i+k)%6]!=b[(j-k+6)%6])break;
            }
            if(k==6)return 1;
        }
    }
    return 0;
}
bool query(int k){
    for(register int i=head[k];i;i=e[i].next){
        if(equal(e[i].sum,a))return 1;
    }
    return 0;
}
int main(){
    int n;    
    scanf("%d",&n);
        bool f=1;
        for(register int i=1;i<=n;++i){
        for(register int j=0;j<6;++j)scanf("%d",&a[j]);
        int k=ha();
        if(query(k)){
            puts("Twin snowflakes found.");
            f=0;
            break;
        }
        ins(k);
        }
        if(f)
        puts("No two snowflakes are alike.");
    
    return 0;
}

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