[BZOJ1834][ZJOI2010]网络扩容（费用流）

题目：

题解：

代码：

#include <cstdio>
#include <queue>
#include <cstring>
#include <iostream>
#define INF 1e9
using namespace std;
const int N=50500;
int maxflow,mincost,tot,nxt
,point
,v
,c
,remind
,dis
,x
,y
,w
;bool vis
;
void addline(int x,int y,int z,int vv)
{
++tot; nxt[tot]=point[x]; point[x]=tot; v[tot]=y; remind[tot]=z; c[tot]=vv;
++tot; nxt[tot]=point[y]; point[y]=tot; v[tot]=x; remind[tot]=0; c[tot]-vv;
}
bool bfs(int s,int t)
{
queue<int>q;q.push(s);
memset(dis,0x7f,sizeof(dis)); dis[s]=0;
while (!q.empty())
{
int now=q.front(); q.pop();
for (int i=point[now];i!=-1;i=nxt[i])
if (dis[v[i]]>INF && remind[i])
{
dis[v[i]]=dis[now]+1; q.push(v[i]);
if (dis[t]<INF) return 1;
}
}
return 0;
}
int didfs(int now,int t,int limit)
{
if (now==t || !limit) return limit;
int flow=0,f;
for (int i=point[now];i!=-1;i=nxt[i])
if (dis[v[i]]==dis[now]+1 && remind[i])
{
f=didfs(v[i],t,min(limit,remind[i]));
flow+=f; limit-=f;
remind[i]-=f; remind[i^1]+=f;
if (!limit) return flow;
}
return flow;
}
int dinic(int s,int t)
{
int ans=0;

fb54
while (bfs(s,t)) ans+=didfs(s,t,INF);
return ans;
}
///dinic
bool spfa(int s,int t)
{
queue<int>q;q.push(s);
memset(vis,0,sizeof(vis));
memset(dis,0x7f,sizeof(dis)); dis[s]=0;
while (!q.empty())
{
int now=q.front(); q.pop(); vis[now]=0;
for (int i=point[now];i!=-1;i=nxt[i])
if (dis[v[i]]>dis[now]+c[i] && remind[i])
{
dis[v[i]]=dis[now]+c[i];
if (!vis[v[i]]) vis[v[i]]=1,q.push(v[i]);
}
}
return dis[t]<INF;
}
int dfs(int now,int t,int limit)
{
vis[now]=1;
if (now==t || !limit) return limit;
int flow=0,f;
for (int i=point[now];i!=-1;i=nxt[i])
if (!vis[v[i]] && dis[v[i]]==dis[now]+c[i] && remind[i])
{
f=dfs(v[i],t,min(limit,remind[i]));
flow+=f; limit-=f;
remind[i]-=f; remind[i^1]+=f;
if (!limit) return flow;
}
return flow;
}
void zkw(int s,int t)
{
while (spfa(s,t))
{
memset(vis,0,sizeof(vis));
mincost+=dis[t]*dfs(s,t,INF);
}
}
////
int main()
{
tot=-1;memset(point,-1,sizeof(point));
int n,m,k;scanf("%d%d%d",&n,&m,&k);
for (int i=1;i<=m;i++)
{
int c;scanf("%d%d%d%d",&x[i],&y[i],&c,&w[i]);
addline(x[i],y[i],c,0);
}
maxflow=dinic(1,n);
printf("%d ",maxflow);
for (int i=1;i<=m;i++) addline(x[i],y[i],INF,w[i]);
addline(0,1,k,0);
zkw(0,n);
printf("%d",mincost);
}