【BZOJ-3144】切糕最小割-最大流

#include
#include
#include
#include
#include
using namespace std;
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;
}
#define maxn 50*50*50
#define maxm 1000100
int p,q,r,d,ans;
int val[50][50][50];
struct Edgenode{int to,next,cap;}edge[maxm];
int head[maxn],cnt=1;
void add(int u,int v,int w)
{cnt++;edge[cnt].to=v;edge[cnt].cap=w;edge[cnt].next=head[u];head[u]=cnt;}
void insert(int u,int v,int w)
{add(u,v,w);add(v,u,0);}
//
int dis[maxn],que[maxn<<1],cur[maxn],S,T;
bool bfs()
{
    for (int i=S; i<=T; i++) dis[i]=-1;
    que[0]=S; dis[S]=0; int he=0,ta=1;
    while (he<ta)
        {
            int now=que[he++];
            for (int i=head[now]; i; i=edge[i].next)
                if (edge[i].cap && dis[edge[i].to]==-1)
                    dis[edge[i].to]=dis[now]+1,que[ta++]=edge[i].to;
        }
    return dis[T]!=-1;
}
int dfs(int loc,int low)
{
    if (loc==T) return low;
    int w,used=0;
    for (int i=cur[loc]; i; i=edge[i].next)
        if (edge[i].cap && dis[edge[i].to]==dis[loc]+1)
            {
                w=dfs(edge[i].to,min(low-used,edge[i].cap));
                edge[i].cap-=w; edge[i^1].cap+=w;
                used+=w; if (edge[i].cap) cur[loc]=i;
                if (used==low) return low;
            }
    if (!used) dis[loc]=-1;
    return used;
}
#define inf 0x7fffffff
int dinic()
{
    int tmp=0;
    while (bfs())
        {
            for (int i=S; i<=T; i++) cur[i]=head[i];
            tmp+=dfs(S,inf);
        }
    return tmp;
}//
int loc(int x,int y,int z)
{if (z==0) return 0;return (z-1)*p*q+(x-1)*q+y;}
void make()
{
    S=0,T=p*q*r+1;
    for (int i=1; i<=p; i++)
        for (int j=1; j<=q; j++)
            {
                for (int k=1; k<=r; k++)
                    {
                        insert(loc(i,j,k-1),loc(i,j,k),val[i][j][k]);
                        if(k>d)
                            {
                                if (i-1>=1) insert(loc(i,j,k),loc(i-1,j,k-d),inf);
                                if (i+1<=p) insert(loc(i,j,k),loc(i+1,j,k-d),inf);
                                if (j-1>=1) insert(loc(i,j,k),loc(i,j-1,k-d),inf);
                                if (j+1<=q) insert(loc(i,j,k),loc(i,j+1,k-d),inf);
                            }

                    }
                insert(loc(i,j,r),T,inf);
            }
}
int main()
{
    p=read(),q=read(),r=read(); d=read();
    for (int i=1; i<=r; i++)
        for (int j=1; j<=p; j++)
            for (int k=1; k<=q; k++)
                val[j][k][i]=read();
    make();
    ans=dinic();
    printf("%d\n",ans);
    return 0;
}