UVa 10911 Forming Quiz Teams / 状态压缩DP

#include <cstdio>
#include <cstring>
#include <algorithm>
#include <cmath>
using namespace std;
const int maxn = 18;
double dp[1<<maxn];
double x[maxn];
double y[maxn];

double d(int i, int j)
{
	return sqrt((x[i]-x[j])*(x[i]-x[j])+(y[i]-y[j])*(y[i]-y[j]));
}
int main()
{
	int cas = 1;
	int n;
	while(scanf("%d", &n) && n)
	{
		n *= 2;
		for(int i = 0; i < n; i++)
		{
			char s[100];
			scanf("%s %lf %lf", s, &x[i], &y[i]);
		}
		dp[0] = 0;
		for(int s = 1; s < (1<<n); s++)
		{
			int i, j;
			dp[s] = 0x7fffffff;
			for(i = 0; i < n; i++)
				if(s&(1<<i))
					break;
			for(int j = i+1; j < n; j++)
			{
				if(s&(1<<j))
				{
					dp[s] = min(dp[s], dp[s^(1<<i)^(1<<j)]+d(i, j));
				}
			}
		}
		printf("Case %d: %.2lf\n", cas++, dp[(1<<n)-1]);  
	}
	return 0;
}
/*
5
 sohel 10 10
 mahmud 20 10
 sanny 5 5
 prince 1 1
 per 120 3
 mf 6 6
 kugel 50 60
 joey 3 24
 limon 6 9
 manzoor 0 0
 1
 derek 9 9
 jimmy 10 10
*/