bzoj 2756

2756

思路：

　　二分讨论，网络流检验；

代码：

#include <bits/stdc++.h>
using namespace std;
#define INF 1e16
#define maxn 40005
#define ll long long
const ll dx[]={,-,,,};
const ll dy[]={,,,,-};
ll ai[][],id[][],suma,sumb,cnta,cntb,que[maxn],Max,ans;
ll deep[maxn],E[maxn],V[maxn],F[maxn],cnt,head[maxn],s,t,cntid;
ll n,m;
bool col[][];
inline void in(ll &now)
{
    char Cget=getchar();now=;
    while(Cget>''||Cget<'') Cget=getchar();
    while(Cget>=''&&Cget<='')
    {
        now=now*+Cget-'';
        Cget=getchar();
    }
}
inline void edge_add(ll u,ll v,ll f)
{
    E[++cnt]=head[u],V[cnt]=v,F[cnt]=f,head[u]=cnt;
    E[++cnt]=head[v],V[cnt]=u,F[cnt]=,head[v]=cnt;
}
bool bfs()
{
    for(ll i=s;i<=t;i++) deep[i]=-;
    deep[s]=,que[]=s;ll h=,tail=,now;
    while(h<tail)
    {
        now=que[h++];
        for(ll i=head[now];i;i=E[i])
            if(F[i]&&deep[V[i]]==-)
            {
                deep[V[i]]=deep[now]+;
                if(V[i]==t) return true;
                que[tail++]=V[i];
            }
    }
    return false;
}
ll flowing(ll now,ll flow)
{
    if(now==t||flow<=) return flow;
    ll oldflow=,pos;
    for(ll i=head[now];i;i=E[i])
    {
        if(!F[i]||deep[V[i]]!=deep[now]+) continue;
        pos=flowing(V[i],min(flow,F[i]));
        F[i]-=pos,F[i^]+=pos,oldflow+=pos,flow-=pos;
        if(!flow) return oldflow;
    }
    if(!oldflow) deep[now]=-;
    return oldflow;
}
bool check(ll x)
{
    for(ll i=s;i<=t;i++) head[i]=;cnt=;
    for(ll i=;i<=n;i++)
        for(ll v=;v<=m;v++)
            if(col[i][v])
            {
                edge_add(s,id[i][v],x-ai[i][v]);
                for(ll e=;e<=;e++)
                    if(i+dx[e]>&&i+dx[e]<=n&&v+dy[e]>&&v+dy[e]<=m) edge_add(id[i][v],id[i+dx[e]][v+dy[e]],INF);
            }
            else edge_add(id[i][v],t,x-ai[i][v]);
    ll res=;
    while(bfs()) res+=flowing(s,INF);
    return res==(x*cnta-suma);
}
int main()
{
    freopen("data.txt","r",stdin);
    ll T;in(T);
    while(T--)
    {
        in(n),in(m),suma=,sumb=,cnta=,cntb=,cntid=,Max=;
        for(ll i=;i<=n;i++)
            for(ll v=;v<=m;v++)
            {
                in(ai[i][v]),col[i][v]=(i+v)%;
                if(col[i][v]) suma+=ai[i][v],cnta++;
                else sumb+=ai[i][v],cntb++;
                id[i][v]=++cntid,Max=max(Max,ai[i][v]);
            }
        ans=-,s=,t=cntid+;
        if(cnta!=cntb)
        {
            if((suma-sumb)%(cnta-cntb)==)
            {
                ll x=(suma-sumb)/(cnta-cntb);
                if(x>=Max) if(check(x)) ans=x*cnta-suma;
            }
        }
        else
        {
            if(suma==sumb)
            {
                ll l=Max,r=INF,mid;
                while(l<=r)
                {
                    mid=l+r>>;
                    if(check(mid)) r=mid-,ans=mid;
                    else l=mid+;
                }
                if(ans!=-) ans=ans*cnta-suma;
            }
        }
        printf("%lld\n",ans);
    }
    return ;
}