【网络流#3】hdu 1532 - Dinic模板题

  1 #include<cstdio>
  2 #include<cstring>
  3 #include<cmath>
  4 #include<iostream>
  5 #include<algorithm>
  6 #include<set>
  7 #include<map>
  8 #include<stack>
  9 #include<vector>
 10 #include<queue>
 11 #include<string>
 12 #include<sstream>
 13 #define MAXN 200
 14 #define MAXM 400
 15 #define INF (1<<30)
 16 #define eps 0.000001
 17 #define ALL(x) x.begin(),x.end()
 18 #define INS(x) inserter(x,x.begin())
 19 using namespace std;
 20 int i,j,k,n,m,x,y,T,num,w;
 21 
 22 const int inf = 0x3f3f3f3f;
 23 struct edgenode
 24 {
 25     int from,to,next;
 26     int cap;
 27 }edge[MAXM];
 28 int Edge,head[MAXN],ps[MAXN],dep[MAXN];
 29 
 30 void addedge(int x,int y,int c)
 31 {
 32     edge[Edge].from=x;
 33     edge[Edge].to=y;
 34     edge[Edge].cap=c;
 35     edge[Edge].next=head[x];
 36     head[x]=Edge++;
 37     
 38     edge[Edge].from=y;
 39     edge[Edge].to=x;
 40     edge[Edge].cap=0;
 41     edge[Edge].next=head[y];
 42     head[y]=Edge++;
 43 }
 44 
 45 int dinic(int n,int s,int t)
 46 {
 47     int tr,flow=0;
 48     int i,j,k,l,r,top;
 49     while(1){
 50         memset(dep,-1,(n+1)*sizeof(int));
 51         for(l=dep[ps[0]=s]=0,r=1;l!=r;)//BFS部分，将给定图分层 
 52         {
 53             for(i=ps[l++],j=head[i];j!=-1;j=edge[j].next)
 54             {
 55                 if (edge[j].cap&&-1==dep[k=edge[j].to])
 56                 {
 57                     dep[k]=dep[i]+1;ps[r++]=k;
 58                     if(k==t)
 59                     {
 60                         l=r;
 61                         break;
 62                     }
 63                 }
 64             }
 65         }
 66         if(dep[t]==-1)break;
 67         
 68         for(i=s,top=0;;)//DFS部分 
 69         {
 70             if(i==t)//当前点就是汇点时 
 71             {
 72                 for(k=0,tr=inf;k<top;++k)
 73                     if(edge[ps[k]].cap<tr)tr=edge[ps[l=k]].cap;
 74                     
 75                 for(k=0;k<top;++k)
 76                     edge[ps[k]].cap-=tr,edge[ps[k]^1].cap+=tr;
 77                     
 78                 flow+=tr;
 79                 i=edge[ps[top=l]].from;
 80             }
 81             
 82             for(j=head[i];j!=-1;j=edge[j].next)//找当前点所指向的点 
 83                 if(edge[j].cap&&dep[i]+1==dep[edge[j].to]) break;
 84                 
 85             if(j!=-1)
 86             {
 87                 ps[top++]=j;//当前点有所指向的点，把这个点加入栈中 
 88                 i=edge[j].to;
 89             }
 90             else
 91             { 
 92                 if (!top) break;//当前点没有指向的点，回溯 
 93                 dep[i]=-1;
 94                 i=edge[ps[--top]].from;
 95             }
 96         }
 97     }
 98     return flow;
 99 }
100 
101 int main()
102 {
103     int T,cas,m,s,t,n,maxflow,i;
104     int x,y,c;
105     double ans;
106     while(~scanf("%d%d",&m,&n))
107     {   
108         memset(head,-1,sizeof(head));
109         Edge=0;
110         for(i=0;i<m;i++)
111         {
112             scanf("%d%d%d",&x,&y,&c);
113             addedge(x,y,c);
114         }
115         printf("%d\n",dinic(n,1,n));
116     }
117     return 0;
118 }