【费用流】【Next Array】费用流模板(spfa版)

一、非结构体版

 1 #include<cstdio>
 2 #include<algorithm>
 3 #include<cstring>
 4 #include<queue>
 5 using namespace std;
 6 #define MAXN 501
 7 #define MAXM 50001
 8 #define INF 2147483647
 9 int S,T;
10 int en,u[MAXM],v[MAXM],first[MAXN],next[MAXM],cap[MAXM],cost[MAXM];//Next Array
11 bool inq[MAXN];
12 int d[MAXN]/*spfa*/,p[MAXN]/*spfa*/,a[MAXN]/*可改进量*/;
13 queue<int>q;
14 void Init_MCMF(){memset(first,-1,sizeof(first));en=0;}
15 void AddEdge(const int &U,const int &V,const int &W,const int &C)
16 {
17     u[en]=U; v[en]=V; cap[en]=W; cost[en]=C;
18     next[en]=first[U];
19     first[U]=en++;
20     u[en]=V; v[en]=U; cost[en]=-C;
21     next[en]=first[V];
22     first[V]=en++;
23 }
24 bool Spfa(int &Flow,int &Cost)
25 {
26     memset(d,0x7f,sizeof(d));
27     memset(inq,0,sizeof(inq));
28     d[S]=0; inq[S]=1; p[S]=0; a[S]=INF; q.push(S);
29     while(!q.empty())
30       {
31           int U=q.front(); q.pop(); inq[U]=0;
32           for(int i=first[U];i!=-1;i=next[i])
33             if(cap[i] && d[v[i]]>d[U]+cost[i])
34               {
35                 d[v[i]]=d[U]+cost[i];
36                 p[v[i]]=i;
37                 a[v[i]]=min(a[U],cap[i]);
38                 if(!inq[v[i]]) {q.push(v[i]); inq[v[i]]=1;}
39               }
40       }
41     if(d[T]>2000000000) return 0;
42     Flow+=a[T]; Cost+=d[T]*a[T]; int U=T;
43     while(U!=S)
44       {
45           cap[p[U]]-=a[T]; cap[p[U]^1]+=a[T];
46           U=u[p[U]];
47       }
48     return 1;
49 }
50 int Mincost()
51 {
52     int Flow=0,Cost=0;
53     while(Spfa(Flow,Cost));
54     return Cost;
55 }

二、结构体版

 1 #include<cstdio>
 2 #include<algorithm>
 3 #include<cstring>
 4 #include<queue>
 5 using namespace std;
 6 #define MAXN 5001
 7 #define MAXM 100001
 8 #define INF 2147483647
 9 int S,T,n,m;
10 int en,first[MAXN];
11 struct NextArray{int u,v,cap,cost,next;}NA[MAXM];
12 bool inq[MAXN];
13 int d[MAXN]/*spfa*/,p[MAXN]/*spfa*/,a[MAXN]/*可改进量*/;
14 queue<int>q;
15 void Init_MCMF(){en=0;memset(first,-1,sizeof(first));}
16 void AddEdge(const int &U,const int &V,const int &W,const int &C)
17 {
18     NA[en].u=U; NA[en].v=V; NA[en].cap=W; NA[en].cost=C;
19     NA[en].next=first[U]; first[U]=en++;
20     NA[en].u=V; NA[en].v=U; NA[en].cost=-C;
21     NA[en].next=first[V]; first[V]=en++;
22 }
23 bool Spfa(int &Flow,int &Cost)
24 {
25     memset(d,0x7f,sizeof(d));
26     memset(inq,0,sizeof(inq));
27     d[S]=0; inq[S]=1; p[S]=0; a[S]=INF; q.push(S);
28     while(!q.empty())
29       {
30           int U=q.front(); q.pop(); inq[U]=0;
31           for(int i=first[U];i!=-1;i=NA[i].next)
32             if(NA[i].cap && d[NA[i].v]>d[U]+NA[i].cost)
33               {
34                 d[NA[i].v]=d[U]+NA[i].cost;
35                 p[NA[i].v]=i;
36                 a[NA[i].v]=min(a[U],NA[i].cap);
37                 if(!inq[NA[i].v]) {q.push(NA[i].v); inq[NA[i].v]=1;}
38               }
39       }
40     if(d[T]>2000000000) return 0;
41     Flow+=a[T]; Cost+=d[T]*a[T]; int U=T;
42     while(U!=S)
43       {
44           NA[p[U]].cap-=a[T]; NA[p[U]^1].cap+=a[T];
45           U=NA[p[U]].u;
46       }
47     return 1;
48 }
49 int Mincost()
50 {
51     int Flow=0,Cost=0;
52     while(Spfa(Flow,Cost));
53     return Cost;
54 }