YSU小吃街

• 贪心贪不过，暴力搜就完事了
• 注意不连通情况

• #include<iostream>
  #include<sstream>
  #include<cstdio>
  #include<cstdlib>
  #include<string>
  #include<cstring>
  #include<algorithm>
  #include<functional>
  #include<iomanip>
  #include<numeric>
  #include<cmath>
  #include<queue>
  #include<vector>
  #include<set>
  #include<map>
  #include<cctype>
  const double PI = acos(-1.0);
  const int INF = 0x3f3f3f3f;
  const int NINF = -INF - 1;
  const int maxn = 1e5 + 5;
  typedef long long ll;
  #define MOD 1000000007
  using namespace std;
  int n, m, st;
  int vis[maxn];
  int rec = 0;
  typedef pair<int, int> P;
  struct node
  {
      int next, cost;
      int flag;
  };
  vector<node> G[maxn];
  void bfs()
  {
      queue<P> q;
      q.push(P(1, st));
      while(q.size())
      {
          P p = q.front();
          q.pop();
          for(int i = 0; i < G[p.first].size(); ++i)
          {
              node tmp = G[p.first][i];
              int mp;
              if(!tmp.flag) mp = p.second - tmp.cost;
              else mp = p.second + tmp.cost;
              if (vis[tmp.next] == -1) {
                  vis[tmp.next] = mp;
                  q.push(P(tmp.next, vis[tmp.next]));
              }
              else{
                  if(vis[tmp.next] != mp) {
                      rec = 1;
                      break;
                  }
              }
          }
          if(rec) break;
      }
  }
  int main()
  {
      memset(vis, -1, sizeof(vis));
      scanf("%d %d %d", &n, &m, &st);
      for(int i = 0; i < m; ++i)
      {
          int x, y, w;
          scanf("%d %d %d", &x, &y, &w);
          G[x].push_back(node{y, w, 0});
          G[y].push_back(node{x, w, 1});
      }
      vis[1] = st;
      bfs();
  //    for(int i = 1; i <= n; ++i)
  //    {
  //        cout << vis[i] << ' ';
  //    }
  //    cout << endl;
      for(int i = 1; i <= n; ++i)
      {
          if(vis[i] == -1)
          {
              rec = 1;
              break;
          }
      }
      if(rec)
      {
          cout << "QAQ";
      }
      else
      {
          cout << "QWQ" << endl;
          for(int i = 1; i <= n; ++i)
          {
              cout << vis[i] << endl;
          }
      }
      return 0;
  }