C. Captain Marmot （Codeforces Round #271)
Captain Marmot wants to prepare a huge and important battle against his enemy, Captain Snake. For this battle he has n regiments, each consisting of 4 moles.
Initially, each mole i (1 ≤ i ≤ 4n) is placed at some position (xi, yi) in the Cartesian plane. Captain Marmot wants to move some moles to make the regiments compact, if it's possible.
Each mole i has a home placed at the position (ai, bi). Moving this mole one time means rotating his position point (xi, yi) 90 degrees counter-clockwise around it's home point (ai, bi).
A regiment is compact only if the position points of the 4 moles form a square with non-zero area.
Help Captain Marmot to find out for each regiment the minimal number of moves required to make that regiment compact, if it's possible.
The first line contains one integer n (1 ≤ n ≤ 100), the number of regiments.
The next 4n lines contain 4 integers xi, yi, ai, bi ( - 104 ≤ xi, yi, ai, bi ≤ 104).
Print n lines to the standard output. If the regiment i can be made compact, the i-th line should contain one integer, the minimal number of required moves. Otherwise, on the i-th line print "-1" (without quotes).
4 1 1 0 0 -1 1 0 0 -1 1 0 0 1 -1 0 0 1 1 0 0 -2 1 0 0 -1 1 0 0 1 -1 0 0 1 1 0 0 -1 1 0 0 -1 1 0 0 -1 1 0 0 2 2 0 1 -1 0 0 -2 3 0 0 -2 -1 1 -2 0
1 -1 3 3
In the first regiment we can move once the second or the third mole.
We can't make the second regiment compact.
In the third regiment, from the last 3 moles we can move once one and twice another one.
In the fourth regiment, we can move twice the first mole and once the third mole.
四个点绕给定的中心点逆时针旋转90度，看能否构成正方形，若能。输出最小旋转次数。
每一个点最多旋转3次。4次则回到了原来的位置。就能够用个二维数组把每一个状态记录下来。最后再推断一下是
否能构成正方形即可了。
代码：
#include <iostream>
#include <cstdio>
#include <algorithm>
#include <cstring>
const int inf=9999999;
using namespace std;
struct node
{
int x;
int y;
}p[5][5],home[5];
long long d[8];
long long dis(node a,node b)//距离的平方
{
return (long long)(a.x-b.x)*(a.x-b.x)+(long long)(a.y-b.y)*(a.y-b.y);
}
void solve()
{
int ans=inf;
for(int i=0;i<4;i++)
{
for(int j=0;j<4;j++)
{
for(int k=0;k<4;k++)
{
for(int l=0;l<4;l++)
{
d[0]=dis(p[i][0],p[j][1]);//四边距离的平方
d[1]=dis(p[j][1],p[k][2]);
d[2]=dis(p[k][2],p[l][3]);
d[3]=dis(p[l][3],p[i][0]);
d[4]=dis(p[i][0],p[k][2]);//对角线的平方
d[5]=dis(p[j][1],p[l][3]);
sort(d,d+6);
if(d[0]==0)
continue;
else if(d[0]==d[1]&&d[1]==d[2]&&d[2]==d[3]&&2*d[3]==d[4]&&d[4]==d[5])//推断是否为正方形
{
ans=min(ans,i+j+k+l);
}
}
}
}
}
if(ans!=inf)
printf("%d\n",ans);
else
printf("-1\n");
}
int main()
{
int t;
scanf("%d",&t);
while(t--)
{
for(int i=0;i<4;i++)
{
scanf("%d%d",&p[0][i].x,&p[0][i].y);
scanf("%d%d",&home[i].x,&home[i].y);
int x=p[0][i].x-home[i].x;
int y=p[0][i].y-home[i].y;
p[1][i].x=home[i].x-y;//逆时针旋转90度
p[1][i].y=home[i].y+x;
p[2][i].x=home[i].x-x;
p[2][i].y=home[i].y-y;
p[3][i].x=home[i].x+y;
p[3][i].y=home[i].y-x;
}
solve();
}
return 0;
}
版权声明：本文博主原创文章，博客，未经同意不得转载。
