差分约束 

  1 #include <iostream>
  2 #include <cstdio>
  3 #include <cstdlib>
  4 using namespace std;
  5 
  6 typedef long long ll;
  7 const int MAXN=100010;
  8 const int MAXK=200010;
  9 
 10 struct Edge
 11 {
 12     int next,to;
 13     int w;
 14 }e[MAXK*2];
 15 int head[MAXN],cnt=0;
 16 void addEdge(int x,int y,int z)
 17 {
 18     ++cnt;
 19     e[cnt].next=head[x];
 20     e[cnt].to=y;
 21     e[cnt].w=z;
 22     head[x]=cnt;
 23     return;
 24 }
 25 
 26 int n,k;
 27 ll dis[MAXN];
 28 int num[MAXN];
 29 bool vis[MAXN];
 30 int q[MAXK*2],_head=1,tail=0;
 31 bool SPFA(int s)
 32 {
 33     for (int i=1;i<MAXN;++i) dis[i]=-1;
 34     //queue<int> q;   //被卡了！
 35     //q.push_back(s);
 36     q[++tail]=s;
 37     vis[s]=true;
 38     dis[s]=0;
 39     while (_head<=tail)
 40     {
 41         //int u=q.back();
 42         int u=q[tail];
 43         //q.pop_back();
 44         tail--;
 45         vis[u]=false;
 46         for (int i=head[u];i!=0;i=e[i].next)
 47         {
 48             int v=e[i].to,w=e[i].w;
 49             if (dis[u]+w>dis[v])
 50             {
 51                 dis[v]=dis[u]+w;
 52                 num[v]=num[u]+1;
 53                 if (num[v]>n)
 54                 {
 55                     printf("-1\n");
 56                     exit(0);
 57                 }
 58                 if (!vis[v])
 59                 {
 60                     //q.push_back(v);
 61                     q[++tail]=v;
 62                     vis[v]=true;
 63                 }
 64             }
 65         }
 66     }
 67     return true;
 68 }
 69 
 70 int main()
 71 {
 72     scanf("%d%d",&n,&k);
 73     for (int i=1;i<=k;++i)
 74     {
 75         int x,u,v;
 76         scanf("%d%d%d",&x,&u,&v);
 77         if (x==1) addEdge(u,v,0),addEdge(v,u,0);
 78         else if (x==2)
 79         {
 80             if (u==v) {printf("-1\n");return 0;}
 81             addEdge(u,v,1);
 82         }
 83         else if (x==3) addEdge(v,u,0);
 84         else if (x==4)
 85         {
 86             if (u==v) {printf("-1\n");return 0;}
 87             addEdge(v,u,1);
 88         }
 89         else if (x==5) addEdge(u,v,0);
 90     }
 91     for (int i=1;i<=n;++i) addEdge(0,i,1);   //建立超级源点0
 92 
 93     SPFA(0);   //判断有无解，求解
 94 
 95     ll ans=0;
 96     for (int i=1;i<=n;++i) ans+=dis[i];
 97     printf("%lld\n",ans);
 98 
 99     return 0;
100 }

 

posted @ 2021-12-04 21:16  Hell0er  阅读(45)  评论(0)    收藏  举报