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;

}