"State compression DP" bzoj1087-[scoi2005) non-aggression King

"The main topic"

Put K Kings in NxN's chessboard, so that they do not attack each other, there are many kinds of layout plan. The king can attack it up and down, as well as the left upper left lower right up to the bottom right in the next eight directions in the vicinity of a grid, a total of 8 squares.

Ideas

The feasible state of each row is preprocessed first (i.e. there is no adjacent 1 in a single line) and is stored in the usable.

Then the preprocessing usable between 22 can be converted to each other and stored in the map.

F[i][j][k] line I, has been used to J King, the current line status of Usable[k] situation, the four-cycle violence recursion can be!

Here with the usable the truth should be faster, but with POPOQQQ speed is the same? However, this optimization should be effective!

1#include <iostream>2#include <cstdio>3#include <cstring>4#include <algorithm>5 using namespacestd;6typedefLong Longll;7 Const intmaxn= +;8 Const intmaxk= -;9 Const intmaxm= the;Ten intn,m; One intMAP[MAXN][MAXN]; All F[MAXM][MAXK][MAXN];//F[i][j][k] line I, has been used to J King, the current line state is K - intUSABLE[MAXN]; - intDIGIT[MAXN]; the   - intUsable (intx) - { -     if(x<<1&x | | X>>1&AMP;X)return 0;Else return 1; +     //cannot have adjacent 1 - } +   A intGet_digit (intx) at { -     intret=0; -      while(x) ret+=x&1, x>>=1; -     returnret; - } -   in intJudge (intXinty) - { to     if(X&y | | (x<<1) &y | | (x>>1) &y)return 0;Else return 1; +     /*There are three types of cases that are not feasible*/ - } the   * voidInit () $ {Panax Notoginsengmemset (Usable,0,sizeof(usable)); -memset (Map,0,sizeof(map)); the      for(intI=0;i<1<<n;i++) +         if(Usable (i)) usable[++usable[0]]=i; A     /*pre-processing of a viable state (no adjacent 1 can be left and right)*/ the      for(intI=1; i<=usable[0];i++) +          for(intj=1; j<=usable[0];j++) -         {  $             if(Judge (Usable[i],usable[j])) map[i][j]=1; $         }  -     /*The state of being able to be converted in a feasible state of preprocessing*/ -      for(intI=1; i<=usable[0];i++) digit[i]=get_digit (Usable[i]); the     /*the number of 1 in each feasible state is preprocessed*/ - }Wuyi   the ll DP () - { WuMemset (F,0,sizeof(f)); -f[0][0][1]=1; About      for(intI=1; i<=n;i++) $          for(intj=0; j<=m;j++) -              for(intk=1; k<=usable[0];k++) -                 if(digit[k]<=j) -                 { A                      for(intL=1; l<=usable[0];l++) +                     { the                         if(Map[l][k] && digit[l]+digit[k]<=j) -f[i][j][k]+=f[i-1][j-Digit[k]] [l]; $                     } the                 } thell ret=0; the      for(intI=1; i<=usable[0];i++) ret+=F[n][m][i]; the     returnret; - } in   the intMain () the { Aboutscanf"%d%d",&n,&m); the init (); theCOUT&LT;&LT;DP () <<Endl; the     return 0;  +}

"State compression DP" bzoj1087-[scoi2005) non-aggression King