HDU 1532 Drainage Ditches 最大流 (Edmonds_Karp)

题目链接: http://acm.hdu.edu.cn/showproblem.php?pid=1532

感觉题意不清楚,不知道是不是个人英语水平问题。本来还以为需要维护入度和出度来找源点和汇点呢,看讨论才知道1就是起点,m就是汇点。。好想把代码写的工程化一点。

 1 #include <stdio.h>
 2 #include <string.h>
 3 #include <queue>
 4 #include <algorithm>
 5 using namespace std;
 6 
 7 const int INF = 0x3f3f3f3f;
 8 int n, m;
 9 int cap[210][210], flow[210][210], res[210], pre[210];
10 queue<int>que;
11 
12 int Edmonds_Karp()
13 {
14     while(!que.empty())
15     {
16         que.pop();
17     }
18     int flow_sum = 0;
19     while(true)
20     {
21         memset(res, 0, sizeof(res));
22         res[1] = INF;
23         que.push(1);
24         while(!que.empty())
25         {
26             int u = que.front();
27             que.pop();
28             for(int v = 1; v <= m; v++)
29             {
30                 if(!res[v] && cap[u][v] > flow[u][v])
31                 {
32                     pre[v] = u;
33                     que.push(v);
34                     res[v] = min(res[u], cap[u][v] - flow[u][v]);
35                 }
36             }
37         }
38         if(res[m] == 0)break;
39         for(int u = m; u != 1; u = pre[u])
40         {
41             flow[pre[u]][u] += res[m];
42             flow[u][pre[u]] -= res[m];
43         }
44         flow_sum += res[m];
45     }
46     return flow_sum;
47 }
48 
49 int main()
50 {
51     int u, v, w;
52     while(scanf("%d %d", &n, &m) != EOF)
53     {
54         memset(cap, 0, sizeof(cap));
55         memset(flow, 0, sizeof(flow));
56         for(int i = 0; i < n; i++)
57         {
58             scanf("%d %d %d", &u, &v, &w);
59             cap[u][v] += w;
60         }
61         printf("%d\n", Edmonds_Karp());
62     }
63     return 0;
64 }
View Code

 

posted @ 2013-08-09 17:19  Anti-Magic  阅读(232)  评论(0编辑  收藏  举报