Snowflake Snow Snowflakes poj 3349 哈希

Snowflake Snow Snowflakes

Time Limit: 4000MS		Memory Limit: 65536K
Total Submissions: 39625		Accepted: 10364

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.

/*(1)头文件#include<vector>.

(2)创建vector对象，vector<int> vec;

(3)尾部插入数字：vec.push_back(a);

(4)使用下标访问元素，cout<<vec[0]<<endl;记住下标是从0开始的。

(5)使用迭代器访问元素.

vector<int>::iterator it;
for(it=vec.begin();it!=vec.end();it++)
    cout<<*it<<endl;
(6)插入元素：    vec.insert(vec.begin()+i,a);在第i+1个元素前面插入a;

(7)删除元素：    vec.erase(vec.begin()+2);删除第3个元素

vec.erase(vec.begin()+i,vec.end()+j);删除区间[i,j-1];区间从0开始

(8)向量大小:vec.size();

(9)清空:vec.clear();
*/
#include <iostream>
#include<cstdio>
#include<cstring>
#include<vector>
#include<algorithm>
using namespace std;
const int maxn=100010;
const int pri=100007;
vector<int>hash[pri];
int snow[maxn][6];
int n;
int cmp(int a,int b)
{
       for(int i=0;i<6;i++)
       {
            if(snow[a][0]==snow[b][i%6])//顺时针方向比较;
                if(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])
                      return 1;
                if(snow[a][5]==snow[b][i%6])//逆时针方向
                    if(snow[a][4]==snow[b][(i+1)%6]&&snow[a][3]==snow[b][(i+2)%6]&&snow[a][2]==snow[b][(i+3)%6]
                       &&snow[a][1]==snow[b][(i+4)%6]&&snow[a][0]==snow[b][(i+5)%6])
                       return 1;
       }
       return 0;
}
int main()
{
      scanf("%d",&n);
      int i,j;
      for(i=0;i<n;i++)
      {
          scanf("%d%d%d%d%d%d",&snow[i][0],&snow[i][1],&snow[i][2],&snow[i][3],&snow[i][4],&snow[i][5]);
      }
      int sum,flag=1,key;
      for(i=0;i<n&&flag;i++)
      {
            sum=0;
            for(j=0;j<6;j++)
                sum+=snow[i][j];
            key=sum%pri;
            for(j=0;j<hash[key].size();j++)
            {
                  if(cmp(i,hash[key][j]))
                  {
                      flag=0;
                      puts("Twin snowflakes found.");//有相同的两雪花;
                      break;
                  }
            }
            hash[key].push_back(i);
      }
      if(flag)
        puts("No two snowflakes are alike.");
    return 0;
}