Tour

#include <map>
#include <set>
#include <list>
#include <cmath>
#include <queue>
#include <stack>
#include <cstdio>
#include <vector>
#include <string>
#include <cctype>
#include <complex>
#include <cassert>
#include <utility>
#include <cstring>
#include <cstdlib>
#include <iostream>
#include <algorithm>
using namespace std;
typedef pair<int,int> PII;
typedef long long ll;
#define lson l,m,rt<<1
#define pi acos(-1.0)
#define rson m+1,r,rt<<11
#define All 1,N,1
#define N 1010
#define read freopen("in.txt", "r", stdin)
const ll  INFll = 0x3f3f3f3f3f3f3f3fLL;
const int INF= 0x7ffffff;
const int mod =  1000000007;
double dp[N][N],dis[N][N],x[N],y[N];
int n;
void solve(){
    for(int i=1;i<=n;++i)
        for(int j=1;j<=n;++j)
        dp[i][j]=INF;
    dp[1][1]=0;
    for(int i=2;i<=n;++i)
        for(int j=1;j<=n;++j)
    {
        dp[i][j]=min(dp[i][j],dp[i-1][j]+dis[i][i-1]);
        dp[i][i-1]=min(dp[i][i-1],dp[i-1][j]+dis[j][i]);
    }
    printf("%.2lf\n",dp[n][n-1]+dis[n][n-1]);
}
int main()
{
    while(~scanf("%d",&n)){
        for(int i=1;i<=n;++i){
          scanf("%lf%lf",&x[i],&y[i]);
        }
        for(int i=1;i<=n;++i)
            for(int j=i+1;j<=n;++j){
            dis[i][j]=dis[j][i]=sqrt((x[i]-x[j])*(x[i]-x[j])+(y[i]-y[j])*(y[i]-y[j]));
            }
        solve();
    }
return 0;
}