HDU3549（2）+EK算法

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 1  #include<cstdio>
 2  #include<cstring>
 3  #include<cstdlib>
 4  #include<queue>
 5  using namespace std;
 6  #define N 1005
 7  #define inf 9999999
 8  int map[N][N],path[N],flow[N];
 9  int start,eend,ans,n,m;
10  
11  int bfs(){
12     int t,i;
13     queue<int>q;
14     while(!q.empty())q.pop();
15      memset(path,-1,sizeof(path));
16     path[start]=0;
17     flow[start]=inf;
18     q.push(start);
19     while(!q.empty()){
20         t=q.front();
21         q.pop();
22         if(t==eend)break;
23         for(i=start;i<=eend;i++){//n
24             if(i!=start&&path[i]==-1&&map[t][i]){
25                 flow[i]=flow[t]<map[t][i]?flow[t]:map[t][i];
26                 path[i]=t;
27                 q.push(i);
28             }
29         }
30     }
31     if(path[eend]!=-1)return flow[eend];
32     else return -1;
33 }
34 void ek(){
35     
36     int now,pre,delta;
37     while((delta=bfs())!=-1){
38         ans+=delta;
39         now=eend;
40         while(now!=start){
41             pre=path[now];
42             map[pre][now]-=delta;
43             map[now][pre]+=delta;
44             now=pre;
45         }
46     }
47     return ;
48 }
49  
50  int main()
51  {
52      int i,j,k,tcase,t;
53      int a,b,c;
54      scanf("%d",&tcase);
55      for(t=1;t<=tcase;t++)
56      {
57          scanf("%d%d",&n,&m);
58          start=1;
59          eend=n;
60          memset(map,0,sizeof(map));
61          while(m--)
62          {
63              scanf("%d%d%d",&a,&b,&c);
64              map[a][b]+=c;
65          }
66          ans=0;
67          ek();
68          printf("Case %d: %d\n",t,ans);
69      }
70      return 0;
71  }

EK算法

 

不过还是有点不太明白，EK和Ford—fulkson算法有什么区别。。。。。。。。

posted @ 2012-10-22 22:40  xxx0624  阅读(290)  评论(0)  编辑  收藏  举报