最大流模板

来源：互联网发布：sql时间字符串比较大小编辑：程序博客网时间：2024/05/12 00:31
#include<cstdio>  #include<cstring>  #include<queue>  #include<cmath>  using namespace std;  const int Ni = 210;  const int MAX = 1<<26;  struct Edge{      int u,v,c;      int next;  }edge[20*Ni];  int n,m;  int edn;//边数  int p[Ni];//父亲  int d[Ni];  int sp,tp;//原点，汇点   void addedge(int u,int v,int c)  {      edge[edn].u=u; edge[edn].v=v; edge[edn].c=c;      edge[edn].next=p[u]; p[u]=edn++;       edge[edn].u=v; edge[edn].v=u; edge[edn].c=0;      edge[edn].next=p[v]; p[v]=edn++;  }  int bfs()  {      queue <int> q;      memset(d,-1,sizeof(d));      d[sp]=0;      q.push(sp);      while(!q.empty())      {          int cur=q.front();          q.pop();          for(int i=p[cur];i!=-1;i=edge[i].next)          {              int u=edge[i].v;              if(d[u]==-1 && edge[i].c>0)              {                  d[u]=d[cur]+1;                  q.push(u);              }          }      }      return d[tp] != -1;  }  int dfs(int a,int b)  {      int r=0;      if(a==tp)return b;      for(int i=p[a];i!=-1 && r<b;i=edge[i].next)      {          int u=edge[i].v;          if(edge[i].c>0 && d[u]==d[a]+1)          {              int x=min(edge[i].c,b-r);              x=dfs(u,x);              r+=x;              edge[i].c-=x;              edge[i^1].c+=x;          }      }      if(!r)d[a]=-2;      return r;  }   int dinic(int sp,int tp)  {      int total=0,t;      while(bfs())      {          while(t=dfs(sp,MAX))          total+=t;      }      return total;  }  int main()  {      int i,u,v,c;      while(~scanf("%d%d",&m,&n))      {          edn=0;//初始化          memset(p,-1,sizeof(p));          sp=1;tp=n;          for(i=0;i<m;i++)          {              scanf("%d%d%d",&u,&v,&c);              addedge(u,v,c);          }          printf("%d\n",dinic(sp,tp));      }      return 0;  }
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