poj3349Snowflake Snow Snowflakes(哈希表)

Snowflake Snow Snowflakes
Time Limit: 4000MS Memory Limit: 65536K
Total Submissions: 42252 Accepted: 11099
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.

统计每个雪花边的和，作为哈希的地址标记，这样能快速查找
用vector对数据进行处理，将sum相同的进行push_back，然后再对sum.size()里面的数据进行查找，出现相同的就break

#include <cstdio>#include <cstring>#include <algorithm>#include <iostream>#include <queue>#include <cmath>using namespace std;#define N 100010#define MOD 19999int n;int snow[N][6];vector<int>vec[20000];int isok(int s1,int s2){    for(int i=0;i<6;i++){        int flag=1;        for(int j=0,k=i;j<6;j++,k=(k+1)%6){            if(snow[s1][j]!=snow[s2][k]){                flag=0;                break;            }        }        if(flag) return 1;    }    for(int i=0;i<6;i++){        int flag=1;        for(int j=5,k=i;j>=0;j--,k=(k+1)%6){            if(snow[s1][j]!=snow[s2][k]){                flag=0;                break;            }        }        if(flag) return 1;    }    return 0;}int main(){    scanf("%d",&n);    int flag=0;    for(int i=0;i<n;i++)    {        int sum=0;        for(int j=0;j<6;j++)        {            scanf("%d",&snow[i][j]);            sum+=snow[i][j];        }        if(flag)            continue;        sum=sum%MOD;        for(int j=0;j<vec[sum].size();j++)        {            if(isok(vec[sum][j],i))            {                flag=1;                break;            }        }        vec[sum].push_back(i);    }    if(flag)    cout<<"Twin snowflakes found."<<endl;    else    cout<<"No two snowflakes are alike."<<endl;    return 0;}