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
",ans/4);
	}
	return 0;
}