poj 1185 炮兵阵地

http://poj.org/problem?id=1185

状态压缩+dp

代码：

#include<iostream>
#include<cstdio>
#include<cstring>
#include<string>
#include<map>
#include<set>
#include<vector>
#include<stack>
#include<queue>
#include<algorithm>

#define LL long long
#define ULL unsigned long long
using namespace std;
const int INF=0x3f3f3f3f;
const int MOD=1000000007;
const int N=105;
const int M=205;
char a[N][N];
int b[N],len;
vector<int>vt[N];
vector<int>num[N];
int dp[N][M][M];
int ok(int x,int y)
{
    len=0;
    while(y>0)
    {
        b[len++]=(y&1);
        y=y>>1;
    }
    int sum=0;
    for(int i=0;i<len;++i)
    if(b[i]==1)
    {
        ++sum;
        if((i-2>=0&&b[i-2]==1)||(i-1>=0&&b[i-1]==1)||(a[x][i]=='H'))
        return -1;
    }
    return sum;
}
int main()
{
    //freopen("data.in","r",stdin);
    int n,m;
    while(scanf("%d %d ",&n,&m)!=EOF)
    {
        for(int i=0;i<=n;++i)
        {vt[i].clear();num[i].clear();}
        memset(a,0,sizeof(a));
        for(int i=1;i<=n;++i)
        gets(a[i]);
        for(int i=1;i<=n;++i)
        for(int j=0;j<(1<<m);++j)
        {
            int k=ok(i,j);
            if(k==-1) continue;
            vt[i].push_back(j);
            num[i].push_back(k);
        }
        vt[0].push_back(0);
        num[0].push_back(0);
        memset(dp,-1,sizeof(dp));
        for(unsigned int j=0;j<vt[1].size();++j)
        dp[1][0][j]=num[1][j];
        for(int i=2;i<=n;++i)
        for(unsigned int j=0;j<vt[i-1].size();++j)
        for(unsigned int l=0;l<vt[i].size();++l)
        if((vt[i-1][j]&vt[i][l])==0)
        {
            for(unsigned int r=0;r<vt[i-2].size();++r)
            if((vt[i-2][r]&vt[i-1][j])==0&&(vt[i][l]&vt[i-2][r])==0&&dp[i-1][r][j]!=-1)
            {
                if(dp[i][j][l]==-1||dp[i][j][l]<dp[i-1][r][j]+num[i][l])
                dp[i][j][l]=dp[i-1][r][j]+num[i][l];
            }
        }
        int ans=0;
        for(unsigned int j=0;j<vt[n-1].size();++j)
        for(unsigned int l=0;l<vt[n].size();++l)
        if(dp[n][j][l]!=-1)
        ans=max(ans,dp[n][j][l]);
        printf("%d\n",ans);
    }

    return 0;
}