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  1. //Lib
  2. #include<cstdio>
  3. #include<cstring>
  4. #include<cstdlib>
  5. #include<cmath>
  6. #include<ctime>
  7.  
  8. #include<iostream>
  9. #include<algorithm>
  10. #include<vector>
  11. #include<string>
  12. #include<queue>
  13. #include<stack>
  14. #include<set>
  15. #include<map>
  16. using namespace std;
  17. //Macro
  18. #define rep(i,a,b)  for(int i=a,tt=b;i<=tt;++i)
  19. #define drep(i,a,b) for(int i=a,tt=b;i>=tt;--i)
  20. #define erep(i,e,x) for(int i=x;i;i=e[i].next)
  21. #define irep(i,x)   for(__typeof(x.begin()) i=x.begin();i!=x.end();i++)
  22. #define read()  (strtol(ipos,&ipos,10))
  23. #define sqr(x)  ((x)*(x))
  24. #define pb  push_back
  25. #define PS  system("pause");
  26. typedef long long   ll;
  27. typedef pair<int,int> pii;
  28. const int oo=~0U>>1;
  29. const double inf=1e100;
  30. const double eps=1e-6;
  31. string name="", in=".in", out=".out";
  32. //Var
  33. struct E
  34. {
  35.     int next,node,cap;
  36. }e[10000];
  37. queue<int> q;
  38. int n,node[40][40],dis[1000],h[1000],tot=1,ans,st,ed,cnt;
  39. void add(int a,int b,int c)
  40. {
  41.     e[++tot].next=h[a];e[tot].node=b;e[tot].cap=c;h[a]=tot;
  42.     e[++tot].next=h[b];e[tot].node=a;e[tot].cap=0;h[b]=tot;
  43. }
  44. void Init()
  45. {
  46.     scanf("%d",&n);int t;
  47.     rep(i,1,n)rep(j,1,n)node[i][j]=++cnt;
  48.     st=++cnt;ed=++cnt;
  49.     rep(i,1,n)rep(j,1,n)
  50.     {
  51.         scanf("%d",&t);ans+=t;
  52.         if((i+j-1)&1)
  53.         {
  54.             if(i!=1)add(node[i][j],node[i-1][j],oo);
  55.             if(i!=n)add(node[i][j],node[i+1][j],oo);
  56.             if(j!=1)add(node[i][j],node[i][j-1],oo);
  57.             if(j!=n)add(node[i][j],node[i][j+1],oo);
  58.             add(st,node[i][j],t);
  59.         }
  60.         else add(node[i][j],ed,t);
  61.     }
  62. }
  63. bool BFS()
  64. {
  65.     memset(dis,-1,sizeof dis);
  66.     q.push(ed);dis[ed]=0;
  67.     int u,v;bool flag=false;
  68.     while(!q.empty())
  69.     {
  70.         u=q.front();q.pop();
  71.         erep(i,e,h[u])
  72.         {
  73.             if(dis[v=e[i].node]!=-1||!e[i^1].cap)continue;
  74.             dis[v]=dis[u]+1;
  75.             if(v==st)flag=true;
  76.             q.push(v);
  77.         }
  78.     }
  79.     return flag;
  80. }
  81. int DFS(int u,int low)
  82. {
  83.     if(u==ed)return low;
  84.     int v,tmp,ret=low;
  85.     erep(i,e,h[u])
  86.     {
  87.         if(dis[v=e[i].node]!=dis[u]-1||!e[i].cap)continue;
  88.         tmp=DFS(v,min(low,e[i].cap));
  89.         e[i].cap-=tmp;
  90.         e[i^1].cap+=tmp;
  91.         low-=tmp;
  92.         if(low==0)break;
  93.     }
  94.     if(ret==low)dis[u]=-1;
  95.     return ret-low;
  96. }
  97. void Work()
  98. {
  99.     int flow;
  100.     while(BFS())
  101.         while(flow=DFS(st,oo))
  102.             ans-=flow;
  103.     cout<<ans<<endl;
  104. }
  105. int main()
  106. {
  107. //  freopen((name+in).c_str(),"r",stdin);
  108. //  freopen((name+out).c_str(),"w",stdout);
  109.     Init();
  110.     Work();
  111.     return 0;
  112. }
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https://ideone.com/cA2Ja
language:
C++ (gcc 8.3)
created:
13 years ago
visibility:
public

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