Hash poj2002 Squares

仿照之前的雪花，Hash函数随便搞个。

#include <cstdio>

#include <cstdlib>

#include <cstring>

#include <algorithm>

#include <cmath>

#include <stack>

#include <queue>

#include <vector>

#include <map>

#include <string>

#include <iostream>

const int INF = 9973;

const int kk = 1007;

struct Node

{

	int x;int y; int hash_val;

}node[INF][100];

int Abs(int x)

{

	return x>0?x:-x;

}

int get_hash(Node &a)

{

	a.hash_val= a.x*a.y+a.y*kk;

	return a.hash_val = Abs(a.hash_val)%INF;

}

int Hash(int x,int y)

{

	return Abs(x*y+y*kk)%INF;

}

int len[INF];

void Insert(Node a)

{

	int val=get_hash(a);

	for(int i=0;i<len[a.hash_val];i++)

		if(node[val][i].x==a.x&&node[val][i].y==a.y)

		return ;

	node[val][len[a.hash_val]++]=a;

}

int match(int  x,int y)

{

	int hash1=Hash(x,y);

	for(int i=0;i<len[hash1];i++)

		if(node[hash1][i].x==x&&node[hash1][i].y==y)

		return 1;

	return 0;

}

int main()

{

	int n;

	Node a[20000];

	while(scanf("%d",&n),n){

		memset(node,0,sizeof(node));

		memset(len,0,sizeof(len));

		for(int i=0;i<n;i++){

			scanf("%d%d",&a[i].x,&a[i].y);

			int val=get_hash(a[i]);

			Insert(a[i]);

		}

		int ans=0;

		for(int i=0;i<n;i++){

			for(int j=i+1;j<n;j++){

				int x1=a[i].x-a[i].y+a[j].y;int y1=a[i].y-a[j].x+a[i].x;

				int x2=a[j].x+a[j].y-a[i].y;int y2=a[j].y-a[j].x+a[i].x;

				int x3=a[i].x-a[j].y+a[i].y;int y3=a[i].y-a[i].x+a[j].x;

				int x4=a[j].x-a[j].y+a[i].y;int y4=a[j].y+a[j].x-a[i].x;

				if(match(x1,y1)&&match(x2,y2))

					ans++;

				if(match(x3,y3)&&match(x4,y4))

					ans++;

			}

		}

		printf("%d\n",ans/4);

	}

	return 0;

}