56 lines
1.3 KiB
C++
56 lines
1.3 KiB
C++
#include<stdio.h>
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#include<string.h>
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#include<stdlib.h>
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#include<queue>
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#include<math.h>
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#include<vector>
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#include<map>
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#include<set>
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#include<cmath>
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#include<string>
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#include<algorithm>
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#include<iostream>
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#define exp 1e-10
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#define ll __int64
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using namespace std;
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const int N = 25;
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const int inf = 1000000000;
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const int mod = 1000000007;
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int x[N],y[N],s[6];
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int sqare(int x1,int y1,int x2,int y2)
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{
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return (x2-x1)*(x2-x1)+(y2-y1)*(y2-y1);
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}
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bool judge(int i,int j,int k,int l)
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{
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int t=0;
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s[t++]=sqare(x[i],y[i],x[j],y[j]);
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s[t++]=sqare(x[j],y[j],x[k],y[k]);
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s[t++]=sqare(x[k],y[k],x[l],y[l]);
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s[t++]=sqare(x[l],y[l],x[i],y[i]);
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s[t++]=sqare(x[i],y[i],x[k],y[k]);
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s[t++]=sqare(x[l],y[l],x[j],y[j]);
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sort(s,s+6);
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if(s[0]==s[1]&&s[2]==s[3]&&s[1]==s[2]&&s[4]==2*s[0]&&s[5]==s[4])
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return true;
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return false;
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}
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int main()
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{
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int n,i,j,k,l,t;
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while(~scanf("%d",&n))
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{
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t=0;
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for(i=1;i<=n;i++)
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scanf("%d%d",&x[i],&y[i]);
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for(i=1;i<=n;i++)
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for(j=i+1;j<=n;j++)
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for(k=j+1;k<=n;k++)
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for(l=k+1;l<=n;l++)
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if(judge(i,j,k,l))
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t++;
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printf("%d\n",t);
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}
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return 0;
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}
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