dinic最小费用最大流洛谷 p3381 

 1 #include<bits/stdc++.h>
 2 using namespace std;
 3 typedef long long ll;
 4 const int N = 5e3 + 10;
 5 ll dep[N], h[N], dis[N], vis[N], n, m, s, t, ans1, ans2, ee = 2;
 6 
 7 struct edge{
 8     ll v, next, flow, wage;
 9 }e[100010];
10 void addedge(ll u, ll v, ll flow, ll wage)
11 {
12     e[ee] = (edge){v, h[u], flow, wage};
13     h[u] = ee++;
14 }
15 ll bfs()
16 {
17     memset(vis, 0, sizeof(vis));
18     memset(dis, 0x3f, sizeof(dis));
19     queue<ll>q;
20     q.push(s);
21     dis[s] = 0;
22     vis[s] = 1;
23     while (q.size())
24     {
25         ll u = q.front();
26         q.pop();
27         vis[u] = 0;
28         for(int i = h[u]; i; i = e[i].next)
29         {
30             ll v = e[i].v, w = e[i].wage;
31             if(dis[u] + w < dis[v] && e[i].flow)
32             {
33                 dis[v] = dis[u] + w;
34                 if(!vis[v])
35                 {
36                     q.push(v);
37                     vis[v] = 1;
38                 }
39             }
40         }
41     }
42     return dis[t] != dis[0];
43 }
44 
45 ll dfs(ll u, ll path_misum)
46 {
47     if(u == t)return path_misum;
48     ll ans = 0;
49     vis[u] = 1;
50     for(int i = h[u]; i && path_misum; i = e[i].next)
51     {    
52         ll v = e[i].v;
53         if(!vis[v] && dis[v] == dis[u] + e[i].wage && e[i].flow > 0)
54         {
55             ll other_flow = dfs(v, min(e[i].flow, path_misum));
56             e[i].flow -= other_flow;
57             e[i ^ 1].flow += other_flow;
58             ans += other_flow;
59             path_misum -= other_flow;     
60         }
61     }
62     return ans;
63 }
64 void dinic()
65 {
66     while (bfs())
67     {
68         ll ret = dfs(s, LONG_MAX);
69         ans1 += ret; ans2 += ret * dis[t];
70     }
71 }
72 int main()
73 {
74     ios::sync_with_stdio(false);cin.tie(0);
75     cin >> n >> m >> s >> t;
76     ll u, v, flow, wage;
77     for(int i = 1; i <= m; i++)
78     {
79         cin >> u >> v >> flow >> wage;
80         addedge(u, v, flow, wage);
81         addedge(v, u, 0, -wage);
82     }
83     dinic();
84     cout << ans1 << " " << ans2 << "\n";
85     return 0;
86 }

 

posted @ 2022-05-04 16:38  matt-11  阅读(96)  评论(0)    收藏  举报