[洛谷3381]【模板】最小费用最大流

 1 #include<queue>
 2 #include<cstdio>
 3 #include<cctype>
 4 #include<cstring>
 5 inline int getint() {
 6     char ch;
 7     while(!isdigit(ch=getchar()));
 8     int x=ch^‘0‘;
 9     while(isdigit(ch=getchar())) x=(((x<<2)+x)<<1)+(ch^‘0‘);
10     return x;
11 }
12 const int E=100000,V=5001;
13 const int inf=0x7fffffff;
14 struct Edge {
15     int from,to,remain,cost;
16 };
17 Edge e[E];
18 int g[V][V]={0};
19 int sz=0;
20 inline void add_edge(const int u,const int v,const int w,const int f) {
21     e[sz]=(Edge){u,v,w,f};
22     g[u][++g[u][0]]=sz;
23     sz++;
24 }
25 int n,m,s,t;
26 int a[V],p[V],d[V];
27 bool inq[V];
28 inline int Augment() {
29     memset(a,0,sizeof a);
30     a[s]=inf;
31     std::queue<int> q;
32     q.push(s);
33     memset(inq,0,sizeof inq);
34     inq[s]=true;
35     for(int i=1;i<=n;i++) {
36         d[i]=(i==s)?0:inf;
37     }
38     while(!q.empty()) {
39         int x=q.front();
40         q.pop();
41         inq[x]=false;
42         for(int i=1;i<=g[x][0];i++) {
43             Edge &y=e[g[x][i]];
44             if(y.remain&&(d[x]+y.cost<d[y.to])) {
45                 p[y.to]=g[x][i];
46                 a[y.to]=std::min(a[x],y.remain);
47                 d[y.to]=d[x]+y.cost;
48                 if(!inq[y.to]) {
49                     q.push(y.to);
50                     inq[y.to]=true;
51                 }
52             }
53         }
54     }
55     return a[t];
56 }
57 inline std::pair<int,int> EdmondsKarp() {
58     int maxflow=0,mincost=0;
59     while(int flow=Augment()) {
60         for(int i=t;i!=s;i=e[p[i]].from) {
61             e[p[i]].remain-=flow;
62             e[p[i]^1].remain+=flow;
63         }
64         maxflow+=flow;
65         mincost+=d[t]*flow;
66     }
67     return std::make_pair(maxflow,mincost);
68 }
69 int main() {
70     n=getint(),m=getint(),s=getint(),t=getint();
71     while(m--) {
72         int u=getint(),v=getint(),w=getint(),f=getint();
73         add_edge(u,v,w,f);
74         add_edge(v,u,0,-f);
75     }
76     std::pair<int,int> MCMF=EdmondsKarp();
77     printf("%d %d\n",MCMF.first,MCMF.second);
78     return 0;
79 }