[zoj] 3496 Assignment || 有源汇上下界最大流

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;
}

原文地址：https://www.cnblogs.com/mrha/p/8227942.html