poj3349 Snowflake Snow Snowflakes(HASH)

Posted 2020-10-25 Styx-ferryman

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.
题意:给你最多100000朵雪花,每朵雪花有6条边,如果有两朵雪花经翻转/旋转会重合,则输出"Twin snowflakes found."否则输出"Twin snowflakes found."
题解:只需要hash一下总和,然后遍历总和相同的点,看看是否有重合的雪花
然而这是一道错题emmm详见discuss
代码如下:

#include<queue>
#include<vector>
#include<cstdio>
#include<cstring>
#include<iostream>
#include<algorithm>
#define lson root<<1
#define rson root<<1|1
#define hi puts("hi!");
using namespace std;

vector<int> g[100010];
int n,a[100005][10];

int check(int x,int y)
{
    for(int start=0; start<6; start++)
    {
        if((a[x][1]==a[y][(start+1)%6]&&a[x][2]==a[y][(start+2)%6]&&a[x][3]==a[y][(start+3)%6]&&a[x][4]==a[y][(start+4)%6]&&a[x][5]==a[y][(start+5)%6])
         ||(a[x][1]==a[y][(start+5)%6]&&a[x][2]==a[y][(start+4)%6]&&a[x][3]==a[y][(start+3)%6]&&a[x][4]==a[y][(start+2)%6]&&a[x][5]==a[y][(start+1)%6]))
        {
            return 1;
        }
    }

    return 0;
}

int main()
{
    int flag=0;
    scanf("%d",&n);
    for(int i=1; i<=n; i++)
    {
        scanf("%d%d%d%d%d%d",&a[i][0],&a[i][1],&a[i][2],&a[i][3],&a[i][4],&a[i][5]);
        int key=(a[i][0]+a[i][1]+a[i][2]+a[i][3]+a[i][4]+a[i][5])%99983;
        if(g[key].size())
        {
            for(int j=0; j<g[key].size(); j++)
            {
                if(check(i,g[key][j]))
                {
                    puts("Twin snowflakes found.");
                    flag=1;
                }
            }
        }
        if(flag)
        {
            return 0;
        }
        g[key].push_back(i);
    }
    puts("No two snowflakes are alike.");
}