题目：http://www.lydsy.com/JudgeOnline/problem.php?id=3144
把每一条z轴都拿出来，s->(x,y,1),c=f[x][y][1];(x,y,k)->(x,y,k+1),c=f[x][y][k];(x,y,r)->t,c=inf
然后对于四联通的点，(x,y,z)->(x',y’,z-d)
似乎这叫经典的最小割模型？
#include#include #include #include #include #include #define rep(i,l,r) for (int i=l;i<=r;i++)#define down(i,l,r) for (int i=l;i>=r;i--)#define clr(x,y) memset(x,y,sizeof(x))#define maxn 100050#define ll long long#define inf int(1e9)#define eps 1e-6using namespace std;struct data{ int obj,pre,c;}e[1000500];int n,tot=1,m,r,t,d,f[45][45][45],uu[maxn];int head[maxn],cur[maxn],dx[4]={ 0,1,0,-1},dy[4]={ 1,0,-1,0};int read(){ int x=0,f=1; char ch=getchar(); while (!isdigit(ch)) { if (ch=='-') f=-1; ch=getchar();} while (isdigit(ch)) {x=x*10+ch-'0'; ch=getchar();} return x*f;}int p(int x,int y,int z){ if (z==0) return 0; return (z-1)*n*m+(x-1)*m+y;}void insert(int x,int y,int z){ e[++tot].obj=y; e[tot].pre=head[x]; e[tot].c=z; head[x]=tot; e[++tot].obj=x; e[tot].pre=head[y]; e[tot].c=0; head[y]=tot;}bool jud(int x,int y){ if (x<1||y<1||x>n||y>m) return 0; return 1;}void build(){ rep(i,1,n) rep(j,1,m){ rep(k,1,r) insert(p(i,j,k-1),p(i,j,k),f[i][j][k]); insert(p(i,j,r),t,inf); rep(k,0,3){ int x=i+dx[k],y=j+dy[k]; if (jud(x,y)) rep(o,d+1,r) insert(p(i,j,o),p(x,y,o-d),inf); } } }bool bfs(){ queue q; clr(uu,-1); q.push(0); uu[0]=0; while (!q.empty()){ int u=q.front(); q.pop(); for (int j=head[u];j;j=e[j].pre){ int v=e[j].obj; if (uu[v]==-1&&e[j].c){ uu[v]=uu[u]+1; q.push(v); } } } if (uu[t]==-1) return 0; return 1;}int dfs(int x,int mx){ if (x==t) return mx; int used=0; for (int j=cur[x];j;j=e[j].pre){ int v=e[j].obj; if (uu[v]==uu[x]+1){ int w=dfs(v,min(e[j].c,mx-used)); used+=w; e[j].c-=w; e[j^1].c+=w; if (e[j].c) cur[x]=j; if (used==mx) return mx; } } if (!used) uu[x]=-1; return used;}int dinic(){ int ans=0; while (bfs()){ rep(i,0,t) cur[i]=head[i]; ans+=dfs(0,inf); } return ans;}int main(){ n=read(); m=read(); r=read(); t=n*m*r+1; d=read(); rep(i,1,r) rep(j,1,n) rep(k,1,m) f[j][k][i]=read(); build(); printf("%d\n",dinic()); return 0;}