poj1273 Drainage Ditches

 1 #include <iostream>
 2 #include <cstdio>
 3 #include <queue>
 4 #include <cstring>
 5 using namespace std;
 6 
 7 const int INF = 0x3f3f3f3f;
 8 int m, n, x, y, c;
 9 int G[205][205], pre[205];
10 bool vis[205];
11 
12 int argument()
13 {
14     queue<int> q;
15     q.push(1);
16     memset(pre, 0, sizeof(pre));
17     memset(vis, 0, sizeof(vis));
18     vis[1] = true;
19     bool flag = false;
20     while (!q.empty())
21     {
22         int tmp = q.front();
23         q.pop();
24         for (int i = 1; i <= n; i++)
25         {
26             if (G[tmp][i] && !vis[i])
27             {
28                 pre[i] = tmp;
29                 vis[i] = true;
30                 if (i == n)
31                 {
32                     flag = true;
33                     while (!q.empty())
34                     {
35                         q.pop();
36                     }
37                     break;
38                 }
39                 else
40                     q.push(i);
41             }
42         }
43     }
44     if (!flag)
45     {
46         return 0;
47     }
48     int now = n;
49     int minn = INF;
50     while (pre[now])
51     {
52         minn = min(minn, G[pre[now]][now]);
53         now = pre[now];
54     }
55     now = n;
56     while (pre[now])
57     {
58         G[pre[now]][now] -= minn;
59         G[now][pre[now]] += minn;
60         now = pre[now];
61     }
62     return minn;
63 }
64 int main()
65 {
66     while (cin >> m >> n)
67     {
68         memset(G, 0, sizeof(G));
69         for (int i = 0; i < m; i++)
70         {
71             cin >> x >> y >> c;
72             G[x][y] += c;
73         }
74         int ans = 0;
75         int res = argument();
76         while (res)
77         {
78             ans += res;
79             res = argument();
80         }
81         cout << ans << endl;
82     }
83     return 0;
84 }