%%%，大佬您太强了
正解好像是状压DP
~~然而我用爆搜就水过去了~~
by dblark @ 2018-07-10 10:42:19
%%%模拟退火大佬
by UKE开车自动机 @ 2018-07-10 10:59:13
瞎写的，连这题15的数据都过不了。但是搜索不说，即使是状压DP也是2^n级别的复杂度，再大一点就没得玩了
by fly20040720 @ 2018-07-10 14:40:38
~~莫名90分~~
by SYH123456 @ 2018-08-15 11:05:51
@[Ho0eDdzVW7](/space/show?uid=27950) 我爬山A了啊
by mt19337 @ 2018-08-17 15:21:15
真奇怪
```cpp
#include<bits/stdc++.h>
#define repeat(a,b,c,g) for (int a=b,abck=(g>=0?1:-1);abck*(a)<=abck*(c);a+=g)
using namespace std;
struct point {
double x,y;
}a[20];
int n;
double operator - (point a,point b)
{
return sqrt((a.x-b.x)*(a.x-b.x)+(a.y-b.y)*(a.y-b.y));
}
double calc()
{
double ans=0;
repeat(i,1,n,1)
ans += a[i-1] - a[i];
return ans;
}
int main()
{
srand(233);
cin >> n;
a[0].x = 0;
a[0].y = 0;
repeat(i,1,n,1)
{
cin >> a[i].x >> a[i].y;
}
double MIN = calc();
repeat(_,1,1000,1)
{
repeat(i,1,n,1)
{
swap(a[rand()%n+1],a[i]);
}
repeat(i,1,n,1)
repeat(j,i+1,n,1)
{
double tmp = calc();
MIN = min(tmp,MIN);
swap(a[i],a[j]);
double tp2 = calc();
if (tp2 > tmp)
swap(a[i],a[j]);
MIN = min(tp2,MIN);
}
}
printf("%.2f",MIN);
}
```
by mt19337 @ 2018-08-17 15:21:46