BZOJ 1834: [ZJOI2010]network 网络扩容（网络流+费用流）

一看就知道是模板题= = ，不说什么了= =

PS：回去搞期末了，暑假再来刷题了

CODE：

 #include<cstdio>
 #include<iostream>
 #include<cstring>
 #include<algorithm>
 #include<queue>
 #define maxn 1010
 #define maxm 20010
 #define inf 0x7fffffff
 using namespace std;
 struct edges{
     int to,next,cap,dist;bool b;
 }edge[maxm];
 int n,m,s,t,k,l;
 int next[maxn],dist[maxn],way[maxn],h[maxn],p[maxn],gap[maxn];
 bool b[maxn];
 queue<int> q;
 int addedge(int from,int to,int cap,int dist,bool bo){
     l++;
     edge[l*]=(edges){to,next[from],cap,dist,bo};
     edge[l*+]=(edges){from,next[to],,-dist,bo};
     next[from]=l*;next[to]=l*+;
     return ;
 }
 bool spfa(){
     memset(b,,sizeof(b));
     for (int i=;i<=n;i++) dist[i]=inf;
     dist[]=;
     q.push();
     while (!q.empty()){
     int u=q.front();q.pop();
     b[u]=;
     for (int i=next[u];i;i=edge[i].next)
         if (edge[i].cap&&dist[edge[i].to]>dist[u]+edge[i].dist) {
         dist[edge[i].to]=dist[u]+edge[i].dist;
         way[edge[i].to]=i;
         if(!b[edge[i].to]){
             b[edge[i].to]=;
             q.push(edge[i].to);
         }
         }
     }
     if (dist[t]==inf) return ;
     return ;
 }
 int mcmf(int cap){
     int cost=;
     while (spfa()){
     int x=n,flow=inf;
     while (x!=){
         flow=min(flow,edge[way[x]].cap);
         x=edge[way[x]^].to;
     }
     if (flow>=cap) return (cost+=dist[n]*cap);
     cost+=dist[n]*flow;
     cap-=flow;
     x=n;
     while(x!=){
         edge[way[x]].cap-=flow;
         edge[way[x]^].cap+=flow;
         x=edge[way[x]^].to;
     }
     }
     return cost;
 }
 int sap(int u,int flow){
     if (u==t) return flow;
     int cur=;
     for (int i=p[u];i;i=edge[i].next)
     if (edge[i].b&&edge[i].cap&&h[u]==h[edge[i].to]+){
         int cut=sap(edge[i].to,min(flow-cur,edge[i].cap));
         edge[i].cap-=cut;edge[i^].cap+=cut;
         p[u]=i;
         if ((cur+=cut)==flow ) return flow;
     }
     if (!(--gap[h[u]])) h[s]=n;
     gap[++h[u]]++;
     p[u]=next[u];
     return cur;
 }
 int maxflow(){
     memset(gap,,sizeof(gap));
     memset(h,,sizeof(h));
     gap[]=n;
     for(int i=;i<=n;i++) p[i]=next[i];
     int flow=;
     while (h[s]<n) flow+=sap(s,inf);
     return flow;
 }
 int main(){
     scanf("%d%d%d",&n,&m,&k);
     s=,t=n;
     for (int i=;i<=m;i++) {
     int x,y,cap,d;
     scanf("%d%d%d%d",&x,&y,&cap,&d);
     addedge(x,y,cap,,);
     addedge(x,y,inf,d,);
     }
     int ans=maxflow();
     printf("%d %d\n",ans,mcmf(k));
     return ;
 }