费用流板子
细节真多……一个边的flow和点的flow分不清……还有往回减流的时候应该减去flow[t]……
1 //minamoto 2 #include<iostream> 3 #include<cstdio> 4 #include<queue> 5 #include<algorithm> 6 #include<cstring> 7 using namespace std; 8 #define getc() (p1==p2&&(p2=(p1=buf)+fread(buf,1,1<<21,stdin),p1==p2)?EOF:*p1++) 9 char buf[1<<21],*p1=buf,*p2=buf; 10 inline int read(){ 11 #define num ch-'0' 12 char ch;bool flag=0;int res; 13 while(!isdigit(ch=getc())) 14 (ch=='-')&&(flag=true); 15 for(res=num;isdigit(ch=getc());res=res*10+num); 16 (flag)&&(res=-res); 17 #undef num 18 return res; 19 } 20 const int N=5005,M=100005; 21 bool vis[N]; 22 int n,m,s,t,u,v,e,f,dis[N],Pre[N],last[N],disf[N],maxflow,mincost; 23 int head[N],Next[M],ver[M],edge[M],flow[M],tot=1; 24 queue<int> q; 25 inline void add(int u,int v,int f,int e){ 26 ver[++tot]=v,Next[tot]=head[u],head[u]=tot,edge[tot]=e,flow[tot]=f; 27 ver[++tot]=u,Next[tot]=head[v],head[v]=tot,edge[tot]=-e,flow[tot]=0; 28 } 29 bool spfa(){ 30 memset(dis,0x3f,sizeof(dis)); 31 memset(disf,0x3f,sizeof(disf)); 32 memset(vis,0,sizeof(vis)); 33 q.push(s),vis[s]=1,dis[s]=0,Pre[t]=-1; 34 while(!q.empty()){ 35 int u=q.front();q.pop();vis[u]=0; 36 for(int i=head[u];i;i=Next[i]){ 37 int v=ver[i]; 38 if(flow[i]>0&&dis[v]>dis[u]+edge[i]){ 39 dis[v]=dis[u]+edge[i]; 40 Pre[v]=u; 41 last[v]=i; 42 disf[v]=min(disf[u],flow[i]); 43 if(!vis[v]){ 44 vis[v]=1,q.push(v); 45 } 46 } 47 } 48 } 49 return Pre[t]!=-1; 50 } 51 void MCMF(){ 52 while(spfa()){ 53 int u=t; 54 maxflow+=disf[t]; 55 mincost+=disf[t]*dis[t]; 56 while(u!=s){ 57 flow[last[u]]-=disf[t]; 58 flow[last[u]^1]+=disf[t]; 59 u=Pre[u]; 60 } 61 } 62 } 63 int main(){ 64 n=read(),m=read(),s=read(),t=read(); 65 for(int i=1;i<=m;++i){ 66 u=read(),v=read(),f=read(),e=read(); 67 add(u,v,f,e); 68 } 69 MCMF(); 70 printf("%d %d ",maxflow,mincost); 71 return 0; 72 }