bzoj1834 [ZJOI2010]network 网络扩容（最大流+费用流）

第一问就是直接跑最大流。第二问在残余网络上接着建图，对于原来的每条边，再建一条边容量为inf，费用为w。原边费用为0.建立超级源点向1连边，容量为k，费用为0，跑zkw费用流就好啦

#include <bits/stdc++.h>using namespace std;#define ll long long#define N 1010#define M 5010#define inf 0x3f3f3f3finline int read(){    int x=0,f=1;char ch=getchar();    while(ch<'0'||ch>'9'){if(ch=='-') f=-1;ch=getchar();}    while(ch>='0'&&ch<='9') x=x*10+ch-'0',ch=getchar();    return x*f;}int n,m,K,h[N],num=1,lev[N],mncost=0,pay=0,mc[M<<1];bool vis[N];struct edge{    int fr,to,next,w,c;}data[M<<2];inline void add(int x,int y,int w,int c){    data[++num].to=y;data[num].next=h[x];h[x]=num;data[num].w=w;data[num].c=c;    data[++num].to=x;data[num].next=h[y];h[y]=num;data[num].w=0;data[num].c=-c;    data[num-1].fr=x;data[num].fr=y;}inline bool bfs(){    queue<int>q;memset(lev,0,sizeof(lev));    q.push(1);lev[1]=1;    while(!q.empty()){        int x=q.front();q.pop();        for(int i=h[x];i;i=data[i].next){            int y=data[i].to;if(lev[y]||!data[i].w) continue;            lev[y]=lev[x]+1;q.push(y);        }    }return lev[n];}inline int dinic(int x,int low){    if(x==n) return low;int tmp=low;    for(int i=h[x];i;i=data[i].next){        int y=data[i].to;if(lev[y]!=lev[x]+1||!data[i].w) continue;        int res=dinic(y,min(tmp,data[i].w));        if(!res) lev[y]=0;tmp-=res;data[i].w-=res;data[i^1].w+=res;        if(!tmp) return low;    }return low-tmp;}inline int dinic1(int x,int low){    vis[x]=1;if(x==n){mncost+=low*pay;return low;}int tmp=low;    for(int i=h[x];i;i=data[i].next){        int y=data[i].to;if(vis[y]||data[i].c||!data[i].w) continue;        int res=dinic1(y,min(tmp,data[i].w));        tmp-=res;data[i].w-=res;data[i^1].w+=res;        if(!tmp) return low;    }return low-tmp;}inline bool label(){    int d=inf;    for(int x=0;x<=n;++x){        if(!vis[x]) continue;        for(int i=h[x];i;i=data[i].next){            int y=data[i].to;if(vis[y]||!data[i].w) continue;            d=min(d,data[i].c);        }    }if(d==inf) return 0;    for(int x=0;x<=n;++x){        if(!vis[x]) continue;        for(int i=h[x];i;i=data[i].next) data[i].c-=d,data[i^1].c+=d;    }pay+=d;return 1;}int main(){//  freopen("a.in","r",stdin);    n=read();m=read();K=read();    while(m--){        int x=read(),y=read(),w=read();add(x,y,w,0);mc[num-1]=read();    }int mxflow=0;while(bfs()) mxflow+=dinic(1,inf);    printf("%d ",mxflow);int numm=num;add(0,1,K,0);    for(int i=2;i<=numm;i+=2) add(data[i].fr,data[i].to,inf,mc[i]);    do do memset(vis,0,sizeof(vis));while(dinic1(0,inf));while(label());    printf("%d\n",mncost);    return 0;}