题目链接【https://www.oj.swust.edu.cn/problem/show/2480】
题意:中文题目。
题解:二进制状态转移+坏点判断。
#include<cstdio>
#include<cstring>
#include<algorithm>
using namespace std;
typedef long long LL;
const int maxn = << ;
LL dp[][maxn];
int mp[];
char s[];
int n, m;
int cur;
void DFS(int r, int pos, int nu, int z, int cnt)
{
if(pos == m)
{
dp[cur][nu] = max(dp[cur][nu], dp[cur ^ ][z] + cnt);
return ;
}
if(mp[r] & ( << pos)) //坏点
{
DFS(r, pos + , nu, z, cnt);
return ;
}
if(!(z & ( << pos)) && !(mp[r - ] & ( << pos)))
DFS(r, pos + , nu | ( << pos), z, cnt + );
else
{
if( pos && !(nu & ( << (pos - ))) && !(mp[r] & ( << (pos - ))) )
DFS(r, pos + , nu | ( << pos) | ( << (pos - )), z, cnt + );
DFS(r, pos + , nu, z, cnt);
}
}
int main ()
{
while(~scanf("%d%d", &n, &m))
{
memset(mp, , sizeof(mp));
for(int i = ; i <= n; i++)
{
scanf("%s", s);
for(int j = ; j < m; j++)
if(s[j] == '*') mp[i] |= << j;
}
cur = ;
memset(dp[], -, sizeof(dp[]));
int mask = ( << m) - ;
dp[][mask] = ;
for(int i = ; i <= n; i++)
{
cur ^= ;
memset(dp[cur], -, sizeof(dp[cur]));
for(int j = ; j <= mask; j++)
if(dp[cur ^ ][j] >= )
DFS(i, , , j, );
}
LL ans = ;
for(int i = ; i <= mask; i++)
ans = max(ans, dp[cur][i]);
printf("%lld\n", ans);
}
return ;
}