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Re:请教:这题要是改成旋转后相同不重复计算,该怎么做呢??

Posted by blackRats at 2013-11-07 00:36:20 on Problem 2411
In Reply To:请教:这题要是改成旋转后相同不重复计算,该怎么做呢?? Posted by:richardxx at 2007-09-17 21:44:09
中间对称优化下……即算n/2行即可。
100MS内,状态压缩DP

#include <cstring>
#include <cstdio>
#include <algorithm>
#include <iostream>
using namespace std;

#define LL long long 
LL dp[12][1<<11];
int n,m;

bool ok(int a,int b)
{
	if(a&b) return false;
	a|=b;

	bool two=false;
	int t=m;
	while(t--)
	{
		if(!(a&1))
		{
			if(two)
				two=false;
			else
				two=true;
		}
		else if(two)
			return false;
		a>>=1;
	}
	if(two) return false;
	return true;
}

int main()
{
	while(scanf("%d%d",&n,&m),n||m)
	{
		if( n%2 && m%2 ) { puts("0"); continue; }

		memset(dp,0,sizeof(dp));
		dp[0][0]=1;

		int total=1<<m;
		int a=n/2,b=(n-1)/2;
		for(int i=1;i<=a;i++)
			for(int j=0;j<total;j++) if(dp[i-1][j])
				for(int k=0;k<total;k++) if(ok(k,j))
					dp[i][k]+=dp[i-1][j];

		LL ans=0;
		for(int j=0;j<total;j++) if(dp[a][j])
			for(int k=0;k<total;k++) if(ok(k,j))
				ans+=dp[a][j]*dp[b][k];
		printf("%I64d\n",ans);
	}
}

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