[zoj] 3496 Assignment || 有源汇上下界最大流

Posted 2020-10-20 Mrha

有源汇上下界最大流+二分

原题

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#include<cstdio>
#include<algorithm>
#include<cstring>
#define N 510
#define M 10010
#define inf 0x3f3f3f3f
typedef long long ll;
using namespace std;
struct hhh
{
    int to,next;
    ll w;
}edge[2*M];
int Q,n,m,s,t,p,ss,tt,sum,q[N],x,y,cnt=1,head[N],dis[N],cur[N],tot,u[M],v[M];
ll extra[N],w[M],mx;

ll read()
{
    ll ans=0,fu=1;
    char j=getchar();
    for (;j<\'0\' || j>\'9\';j=getchar()) if (j==\'-\') fu=-1;
    for (;j>=\'0\' && j<=\'9\';j=getchar()) ans*=10,ans+=j-\'0\';
    return ans*fu;
}

void add(int u,int v,ll w)
{
    edge[cnt].to=v;edge[cnt].next=head[u];edge[cnt].w=w;head[u]=cnt++;
    edge[cnt].to=u;edge[cnt].next=head[v];edge[cnt].w=0;head[v]=cnt++;    
}

void ADD(int u,int v,ll b,ll c)
{
    extra[u]-=b;extra[v]+=b;
    add(u,v,c-b);
}

bool bfs(int S,int T)
{
    int r;
    for (int i=0;i<=n+m+3;i++)
	cur[i]=head[i],dis[i]=-1;
    dis[S]=1;
    q[r=1]=S;
    for (int l=1;l<=r;l++)
    {
	int u=q[l];
	for (int i=head[u],v;i;i=edge[i].next)
	    if (edge[i].w>0 && dis[v=edge[i].to]==-1)
	    {
		dis[v]=dis[u]+1;
		q[++r]=v;
		if (v==T) return 1;
	    }
    }
    return 0;
}

ll dfs(int u,ll flow,int T)
{
    if (u==T) return flow;
    ll ret=0,delta;
    for (int &i=cur[u],v;i;i=edge[i].next)
	if (edge[i].w>0 && dis[v=edge[i].to]==dis[u]+1)
	{
	    delta=dfs(v,min(edge[i].w,flow-ret),T);
	    if (delta)
	    {
		edge[i].w-=delta;
		edge[i^1].w+=delta;
		ret+=delta;
		if (ret==flow) break;
	    }
	}
    return ret;
}

ll dinic(int S,int T)
{
    ll ans=0;
    while (bfs(S,T))
	ans+=dfs(S,inf,T);
    return ans;
}

ll buildGraph(ll x,ll y)
{
    cnt=2;
    sum=0;
    memset(head,0,sizeof(head));
    memset(extra,0,sizeof(extra));
    for (int i=1;i<=m;i++)
	ADD(u[i],v[i],x,min(w[i],y));
    for (int i=1;i<=n;i++)
    {
	if (extra[i]>0) add(ss,i,extra[i]),sum+=extra[i];
	if (extra[i]<0) add(i,tt,-extra[i]);
    }
    add(t,s,inf);
    ll tmp=dinic(ss,tt);
    if (tmp!=sum) return -1;
    printf("!%d!\\n",tmp);
    ///*
    for (int i=head[ss];i;i=edge[i].next)
	edge[i].w=edge[i^1].w=0;
    for (int i=head[tt];i;i=edge[i].next)
	edge[i].w=edge[i^1].w=0;
    edge[cnt-1].w=edge[cnt-2].w=0;
    //*/
    return tmp+dinic(s,t);
}

int main()
{
    Q=read();
    int l,r;
    while (Q--)
    {
	scanf("%d%d%d%d%d",&n,&m,&s,&t,&p);
	s++;t++;n++;
	ss=0;tt=n+1;
	if (m==0)
	{
	    printf("0 0\\n");
	    continue;
	}
	for (int i=1;i<=m;i++)
	    u[i]=read()+1,v[i]=read()+1,w[i]=read(),mx=max(mx,w[i]);
	ll mxflow=buildGraph(0,inf);
	l=0;r=mx;
	while (l!=r)// max min
	{
	    int mid=(l+r)>>1;
	    if (buildGraph(0,mid)==mxflow) r=mid;
	    else l=mid+1;
	}
	printf("mxflow: %lld\\n",mxflow);
	printf("%lld ",(ll)l*p);
	l=0;r=mx;
	while (l!=r)//min max
	{
	    int mid=(l+r+1)>>1;
	    printf("::%d %d %d\\n",l,mid,r);
	    int ans=buildGraph(mid,inf);
	    printf("%d\\n",ans);
	    if (ans==mxflow) l=mid;
	    else r=mid-1;
	}
	printf("%lld\\n",(ll)r*p);
    }
    return 0;
}