Squares-暴力枚举或者二分-白红宇

Squares-暴力枚举或者二分

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发布时间：2019-06-13

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B - Squares

Time Limit:3500MS Memory Limit:65536KB 64bit IO Format:%I64d & %I64u

Description

A square is a 4-sided polygon whose sides have equal length and adjacent sides form 90-degree angles. It is also a polygon such that rotating about its centre by 90 degrees gives the same polygon. It is not the only polygon with the latter property, however, as a regular octagon also has this property.

So we all know what a square looks like, but can we find all possible squares that can be formed from a set of stars in a night sky? To make the problem easier, we will assume that the night sky is a 2-dimensional plane, and each star is specified by its x and y coordinates.

Input

The input consists of a number of test cases. Each test case starts with the integer n (1 <= n <= 1000) indicating the number of points to follow. Each of the next n lines specify the x and y coordinates (two integers) of each point. You may assume that the points are distinct and the magnitudes of the coordinates are less than 20000. The input is terminated when n = 0.

Output

For each test case, print on a line the number of squares one can form from the given stars.

Sample Input

41 00 11 10 090 01 02 00 21 22 20 11 12 14-2 53 70 05 20

Sample Output

/*Author: 2486Memory: 24256 KB		Time: 375 MSLanguage: C++		Result: Accepted*///此题目暴力暴力枚举//通过已经确定好的两点，算出剩下的两点//（有两种情况）//一个在上面，一个以下#include 
           
            #include 
            
             #include 
             
              using namespace std;const int maxn=20000+5;struct point{    int x,y;}ps[1005];int n,ans;bool vis[maxn<<1][maxn<<1];int main(){while(~scanf("%d",&n),n){    ans=0;    for(int i=0;i

转载于:https://www.cnblogs.com/lytwajue/p/6971114.html

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