bzoj1834: [ZJOI2010]network 网络扩容

传送门
第一问直接网络流爆过去。
第二问：
在处理完第一问的参量网络上加上流量为inf，费用为w的边。
直接跑最小费用最大流不虚。

#include<cstdlib>  #include<iostream>  #include<cstdio>  #include<cmath>  #include<algorithm>  #include<cstring>using namespace std;const int inf=0x3fffffff;int n,m,k,u,v,w,c,cnt=1,ans,t;int head[1001],inq[1001],dis[1001],from[1001],q[1017];struct edge{int from,to,v,c,t,next;}e[50001];void ins(int u,int v,int w,int c){    e[++cnt].to=v;    e[cnt].from=u;    e[cnt].v=w;    e[cnt].t=c;    e[cnt].next=head[u];    head[u]=cnt;}void ins1(int u,int v,int w,int c){    e[++cnt].to=v;    e[cnt].from=u;    e[cnt].v=w;    e[cnt].c=c;    e[cnt].next=head[u];    head[u]=cnt;}bool bfs(){    int h=0,t=1,x;    memset(dis,-1,sizeof(dis));    q[1]=1;    dis[1]=0;    while (h<t){        x=q[++h];        for (int i=head[x];i;i=e[i].next)            if (e[i].v>0&&dis[e[i].to]==-1){                dis[e[i].to]=dis[x]+1;                q[++t]=e[i].to;            }    }    return dis[n]!=-1;}int dfs(int x,int flow){    if (x==n) return flow;    int k,rest=flow;    for (int i=head[x];i&&rest;i=e[i].next)        if (e[i].v>0&&dis[e[i].to]==dis[x]+1){            k=dfs(e[i].to,min(rest,e[i].v));            e[i].v-=k;            rest-=k;            e[i^1].v+=k;        }    if (rest) dis[x]=-1;    return flow-rest;}bool spfa(){    int h=0,t=1,x;    for (int i=0;i<=n;i++) dis[i]=inf;    dis[0]=q[1]=0;    inq[0]=1;    while (h!=t){        h=h%1001+1;        x=q[h];        inq[x]=0;        for (int i=head[x];i;i=e[i].next)            if (e[i].v&&dis[x]+e[i].c<dis[e[i].to]){                dis[e[i].to]=dis[x]+e[i].c;                from[e[i].to]=i;                if (!inq[e[i].to]){                    inq[e[i].to]=1;                    t=t%1001+1;                    q[t]=e[i].to;                }            }    }    return dis[n]!=inf;}void del(){    int x=inf;    for (int i=from[n];i;i=from[e[i].from]) x=min(x,e[i].v);    for (int i=from[n];i;i=from[e[i].from]){        e[i].v-=x;        e[i^1].v+=x;        ans+=x*e[i].c;    }}int main(){    scanf("%d%d%d",&n,&m,&k);    for (int i=1;i<=m;i++){        scanf("%d%d%d%d",&u,&v,&w,&c);        ins(u,v,w,c);        ins(v,u,0,-c);    }    while (bfs()) ans+=dfs(1,inf);    printf("%d ",ans);    ans=0;    t=cnt;    for (int i=2;i<=t;i+=2){        ins1(e[i].from,e[i].to,inf,e[i].t);        ins1(e[i].to,e[i].from,0,-e[i].t);    }    ins(0,1,k,0);    while (spfa()) del();    printf("%d",ans);}