Description

Input

Output

Sample Input

Sample Output

#include<iostream>
#include<cstdio>
#include<cstring>
#define N 210
#define INF 707406378
using namespace std;
int f[N][N],d[N][N],ans,m,n,x,y,z,p[N][N];
void floyed(){
    for (int k=1;k<=n;k++)
      for (int i=1;i<=n;i++)
        for (int j=1;j<=n;j++)
          if (i!=j&&j!=k&&k!=i){f[i][j]=min(f[i][j],f[i][k]+f[k][j]);}
}
void getrank(){
  for (int i=1;i<=n;i++){
    for (int j=1;j<=n;j++) p[i][j]=j;
    for (int j=1;j<n;j++)
     for (int k=j+1;k<=n;k++)
       if (f[i][p[i][j]]>f[i][p[i][k]]) swap(p[i][j],p[i][k]); 
  } 
}
void getans(){
  ans=INF;
  for (int u=1;u<=n;u++)
   for (int v=1;v<=n;v++)
    if (d[u][v]!=INF){
     ans=min(ans,min(f[u][p[u][n]]<<1,f[v][p[v][n]]<<1));int t=n; 
     for (int i=n-1;i>=1;i--)
      if (f[v][p[u][t]]<f[v][p[u][i]]){ans=min(ans,f[u][p[u][i]]+f[v][p[u][t]]+d[u][v]);t=i;}
    }
}
int main(){
   scanf("%d%d",&n,&m);memset(f,127/3,sizeof(f));memset(d,127/3,sizeof(d));
   for (int i=1;i<=n;i++) f[i][i]=d[i][i]=0;
   for (int i=1;i<=m;i++){scanf("%d%d%d",&x,&y,&z);f[x][y]=f[y][x]=d[x][y]=d[y][x]=z;}
   floyed();getrank();getans();
   cout<<ans<<endl; 
}