Snowflake Snow Snowflakes POJ

Description

You may have heard that no two snowflakes are alike. Your task is to write a program to determine whether this is really true. Your program will read information about a collection of snowflakes, and search for a pair that may be identical. Each snowflake has six arms. For each snowflake, your program will be provided with a measurement of the length of each of the six arms. Any pair of snowflakes which have the same lengths of corresponding arms should be flagged by your program as possibly identical.

Input

The first line of input will contain a single integer n, 0 < n ≤ 100000, the number of snowflakes to follow. This will be followed by n lines, each describing a snowflake. Each snowflake will be described by a line containing six integers (each integer is at least 0 and less than 10000000), the lengths of the arms of the snow ake. The lengths of the arms will be given in order around the snowflake (either clockwise or counterclockwise), but they may begin with any of the six arms. For example, the same snowflake could be described as 1 2 3 4 5 6 or 4 3 2 1 6 5.

Output

If all of the snowflakes are distinct, your program should print the message:
No two snowflakes are alike.
If there is a pair of possibly identical snow akes, your program should print the message:
Twin snowflakes found.

Sample Input

2
1 2 3 4 5 6
4 3 2 1 6 5
Sample Output

Twin snowflakes found.

大致题意：告诉你有n个雪花，每个雪花有6个花瓣，每个花瓣有一个值，如果两个雪花存在从某个起点顺时针或逆时针方向的数列相同，则这两个雪花相同，如果这n个雪花都不相同则输出No two snowflakes are alike.，否则输出Twin snowflakes found.

思路：将六个花瓣的值相加对某数取余作为key存入hash表中，如果某两个花瓣的key值相同，则再比较它们是否相同。

代码如下

#include<iostream>#include<cstdio>#include<cstring>#include<algorithm>#include<queue>#include<vector>#include<cmath>#include<string>#include<map>#define LL long long  using namespace std;const int len=99991; const int maxx=100100;int snow[maxx][6];vector<int>hash[len];bool judge(int a,int b){    for(int i=0;i<6;i++)    {        if( (snow[a][0] == snow[b][i] && snow[a][1] == snow[b][(i+1)%6] && snow[a][2] == snow[b][(i+2)%6] && snow[a][3] == snow[b][(i+3)%6] &&            snow[a][4] == snow[b][(i+4)%6] && snow[a][5] == snow[b][(i+5)%6]) ||            (snow[a][0] == snow[b][i] && snow[a][1] == snow[b][(i+5)%6] && snow[a][2] == snow[b][(i+4)%6] && snow[a][3] == snow[b][(i+3)%6] &&            snow[a][4] == snow[b][(i+2)%6] && snow[a][5] == snow[b][(i+1)%6] ) )            return true;    }    return false;}int main(){    int n;    scanf("%d",&n);    for(int i=0;i<n;i++)    {        for(int j=0;j<6;j++)        scanf("%d",&snow[i][j]);    }    int sum,key;    for(int i=0;i<n;i++)    {        sum=0;        for(int j=0;j<6;j++)        sum+=snow[i][j];        key=sum%len;        for(vector<int>::size_type j=0;j<hash[key].size();j++)        {            if(judge(hash[key][j],i))            {                printf("Twin snowflakes found.\n");               return 0;            }        }        hash[key].push_back(i);    }     printf("%s\n", "No two snowflakes are alike.");    return 0;}