hdu 3549 Flow Problem 网络流

 1 #include<iostream>
 2 #include<cstdio>
 3 #include<cstring>
 4 #include<cstdlib>
 5 #include<cmath>
 6 #include<algorithm>
 7 #include<queue>
 8 #define inf 0x7fffffff
 9 using namespace std;
10 const int maxn=16;
11 
12 int n,m;
13 int graph[maxn][maxn],d[maxn];
14 
15 int bfs()
16 {
17     memset(d,0,sizeof(d));
18     d[1]=1;
19     queue<int> Q;
20     Q.push(1);
21     while (!Q.empty())
22     {
23         int u=Q.front() ;Q.pop() ;
24         for (int v=1 ;v<=n ;v++)
25         {
26             if (!d[v] && graph[u][v]>0)
27             {
28                 d[v]=d[u]+1;
29                 Q.push(v);
30                 if (v==n) return 1;
31             }
32         }
33     }
34     return 0;
35 }
36 
37 int dfs(int u,int flow)
38 {
39     if (u==n || flow==0) return flow;
40     int cap=flow;
41     for (int v=1 ;v<=n ;v++)
42     {
43         if (d[v]==d[u]+1 && graph[u][v]>0)
44         {
45             int x=dfs(v,min(cap,graph[u][v]));
46             cap -= x;
47             graph[u][v] -= x;
48             graph[v][u] += x;
49             if (cap==0) return flow;
50         }
51     }
52     return flow-cap;
53 }
54 
55 int Dinic()
56 {
57     int sum=0;
58     while (bfs()) sum += dfs(1,inf);
59     return sum;
60 }
61 
62 int main()
63 {
64     int t,ncase=1;
65     scanf("%d",&t);
66     while (t--)
67     {
68         scanf("%d%d",&n,&m);
69         int a,b,c;
70         memset(graph,0,sizeof(graph));
71         for (int i=0 ;i<m ;i++)
72         {
73             scanf("%d%d%d",&a,&b,&c);
74             graph[a][b] += c;
75         }
76         printf("Case %d: %d\n",ncase++,Dinic());
77     }
78     return 0;
79 }