XTUOJ 1248 TC or CF 搜索

#include <cstdio>
#include <iostream>
#include <ctime>
#include <vector>
#include <cmath>
#include <map>
#include <queue>
#include <algorithm>
#include <cstring>
using namespace std;
typedef long long LL;
const int N=1e5+5;
const int INF=0x3f3f3f3f;
const int mod=1e9+7;
vector<int>g[55],v[55],op[55];
int belong[55],ret,n,m;
void dfs(int pos,int c,int t1,int t2){
  if(t1>n-3||t2>n-3)return; 
  if(c>=ret)return;
  if(n==pos){
    if(t2+1>n-3)return;
    for(int i=0;i<g[n].size();++i){
      if(op[n][i]==2&&belong[g[n][i]]==1)c+=v[n][i];
    }
    ret=min(ret,c);
    return;
  }
  belong[pos]=1;
  int tmp=0;
  for(int i=0;i<g[pos].size();++i){
    if(op[pos][i]==1&&belong[g[pos][i]]==2)tmp+=v[pos][i];
  }
  dfs(pos+1,c+tmp,t1+1,t2);
  belong[pos]=2;
  for(int i=0;i<g[pos].size();++i){
    if(op[pos][i]==2&&belong[g[pos][i]]==1)c+=v[pos][i];
  }
  dfs(pos+1,c,t1,t2+1);
}
int main()
{
    while(~scanf("%d%d",&n,&m)){
      for(int i=1;i<=n;++i){
        v[i].clear();
        g[i].clear();
        op[i].clear();
      }
      for(int i=1;i<=m;++i){
        int k1,k2,k3;
        scanf("%d%d%d",&k1,&k2,&k3);
         if(k1>k2){
          v[k1].push_back(k3);
          g[k1].push_back(k2);
          op[k1].push_back(1);
         }
         else{
          v[k2].push_back(k3);
          g[k2].push_back(k1);
          op[k2].push_back(2);
         }
      }
      ret=INF;
      belong[1]=1;
      dfs(2,0,1,0);
      printf("%d\n",ret);
    }
    return 0;
}