BZOJ1976: [BeiJing2010组队]能量魔方 Cube

  1 #include<cstdio>
  2 #include<cstdlib>
  3 #include<cmath>
  4 #include<cstring>
  5 #include<algorithm>
  6 #include<iostream>
  7 #include<vector>
  8 #include<map>
  9 #include<set>
 10 #include<queue>
 11 #include<string>
 12 #define inf 1000000000
 13 #define maxn 100000
 14 #define maxm 3000000
 15 #define eps 1e-10
 16 #define ll long long
 17 #define pa pair<int,int>
 18 #define FOR for(int i=1;i<=n;i++)for(int j=1;j<=n;j++)for(int k=1;k<=n;k++)
 19 #define mod 1000000007
 20 using namespace std;
 21 inline int read()
 22 {
 23     int x=0,f=1;char ch=getchar();
 24     while(ch<‘0‘||ch>‘9‘){if(ch==‘-‘)f=-1;ch=getchar();}
 25     while(ch>=‘0‘&&ch<=‘9‘){x=10*x+ch-‘0‘;ch=getchar();}
 26     return x*f;
 27 }
 28 int  n,m,s,t,maxflow,tot=1,ans,mark[50][50][50],head[maxn],cur[maxn],h[maxn],q[maxn];
 29 struct edge{int go,next,v;}e[maxm];
 30 void ins(int x,int y,int z){e[++tot].go=y;e[tot].v=z;e[tot].next=head[x];head[x]=tot;}
 31 void insert(int x,int y,int z){ins(x,y,z);ins(y,x,0);}
 32 void ins2(int x,int y,int z){insert(x,y,z);insert(y,x,z);}
 33 bool bfs()
 34 {
 35     for(int i=s;i<=t;i++)h[i]=-1;
 36     int l=0,r=1;q[1]=s;h[s]=0;
 37     while(l<r)
 38     {
 39         int x=q[++l];
 40         for(int i=head[x];i;i=e[i].next)
 41          if(e[i].v&&h[e[i].go]==-1)
 42          {
 43             h[e[i].go]=h[x]+1;q[++r]=e[i].go;
 44          }
 45     }
 46     return h[t]!=-1;
 47 }
 48 int dfs(int x,int f)
 49 {
 50     if(x==t) return f;
 51     int tmp,used=0;
 52     for(int i=head[x];i;i=e[i].next)
 53      if(e[i].v&&h[e[i].go]==h[x]+1)
 54     {
 55         tmp=dfs(e[i].go,min(e[i].v,f-used));
 56         e[i].v-=tmp;if(e[i].v)cur[x]=i;
 57         e[i^1].v+=tmp;used+=tmp;
 58         if(used==f)return f;       
 59     }
 60     if(!used) h[x]=-1;
 61     return used;
 62 }
 63 void dinic()
 64 {
 65     maxflow=0;
 66     while(bfs())
 67     {
 68         for (int i=s;i<=t;i++)cur[i]=head[i];maxflow+=dfs(s,inf);
 69     }
 70 }
 71 int get()
 72 {
 73     char ch=‘ ‘;
 74     while(ch!=‘?‘&&ch!=‘P‘&&ch!=‘N‘)ch=getchar();
 75     if(ch==‘?‘)return 0;else if(ch==‘P‘)return 1;else return 2;
 76 }    
 77 int main()
 78 {
 79     freopen("input.txt","r",stdin);
 80     freopen("output.txt","w",stdout);
 81     n=read();
 82     FOR mark[i][j][k]=(i-1)*n*n+(j-1)*n+k;
 83     s=0;t=mark[n][n][n]+1;
 84     FOR
 85     {
 86         int x=get();
 87         if((i+j+k)&1)
 88         {
 89         if(x==1)insert(s,mark[i][j][k],inf);
 90         else if(x==2)insert(mark[i][j][k],t,inf);
 91         }
 92         else
 93         {
 94         if(x==1)insert(mark[i][j][k],t,inf);
 95         else if(x==2)insert(s,mark[i][j][k],inf);
 96         }
 97         int res=0;
 98         if(i<n)insert(mark[i][j][k],mark[i+1][j][k],1),ans++;
 99         if(i>1)insert(mark[i][j][k],mark[i-1][j][k],1),ans++;
100         if(j<n)insert(mark[i][j][k],mark[i][j+1][k],1),ans++;
101         if(j>1)insert(mark[i][j][k],mark[i][j-1][k],1),ans++;
102         if(k<n)insert(mark[i][j][k],mark[i][j][k+1],1),ans++;
103         if(k>1)insert(mark[i][j][k],mark[i][j][k-1],1),ans++;
104         //if(!x)insert(s,mark[i][j][k],res),insert(mark[i][j][k],t,res);
105     }
106     dinic();
107     printf("%d\n",(ans>>1)-maxflow);
108     return 0;
109 }