poj1185

状态压缩dp

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

#define MAX_COL_NUM 15
#define MAX_ROW_NUM 105
#define MAX_STAT 2050

struct Status
{
    int row_bit[];
    int last_bit_count;
}status[];

int row_num, col_num;
int grid[MAX_ROW_NUM];
int f[][MAX_STAT][MAX_STAT];
int ans;
int status_cnt;

void input()
{
    scanf("%d%d", &row_num, &col_num);
    for (int i = ; i < row_num; i++)
    {
        char row[MAX_COL_NUM];
        scanf("%s", row);
        int row_bit = ;
        for (int j = ; row[j]; j++)
        {
            if (row[j] == 'H')
            {
                row_bit = (row_bit << ) | ;
            }else
            {
                row_bit = (row_bit << ) | ;
            }
        }
        grid[i] = row_bit;
    }
}

int count_bit(int a)
{
    int ret = ;
    while (a > )
    {
        if (a & )
            ret++;
        a >>= ;
    }
    return ret;
}

bool ok(int bit)
{
    while (bit > )
    {
        if ((bit & ) == )
            return false;
        if ((bit & ) == )
            return false;
        bit >>= ;
    }
    return true;
}

bool ok(int bit, int row)
{
    return (bit & grid[row]) == ;
}

void init()
{
    memset(f, , sizeof(f));
    int col_stat = ;
    for (int i = ; i < col_num; i++)
        col_stat *= ;
    for (int i = ; i < col_stat; i++)
    {
        int temp = i;
        int row_bit[];
        row_bit[] = row_bit[] = ;
        for (int j = ; j < col_num; j++)
        {
            row_bit[] <<= ;
            row_bit[] <<= ;
            row_bit[temp % ] |= ;
            temp /= ;
        }
        if (!ok(row_bit[], ) || !ok(row_bit[], ) || !ok(row_bit[]) || !ok(row_bit[]))
        {
            f[][row_bit[]][row_bit[]] = ;
            continue;
        }
        f[][row_bit[]][row_bit[]] = count_bit(row_bit[]) + count_bit(row_bit[]);
        ans = max(ans, f[][row_bit[]][row_bit[]]);
    }    

}

void make_stat()
{
    int col_stat = ;
    status_cnt = ;
    for (int i = ; i < col_num; i++)
        col_stat *= ;
    for (int i = ; i < col_stat; i++)
    {
        int temp = i;
        int row_bit[];
        row_bit[] = row_bit[] = row_bit[] = ;
        for (int j = ; j < col_num; j++)
        {
            row_bit[] <<= ;
            row_bit[] <<= ;
            row_bit[] <<= ;
            row_bit[temp % ] |= ;
            temp /= ;
        }
        bool conflict = false;
        for (int j = ; j < ; j++)
            if (!ok(row_bit[j]))
            {
                conflict = true;
                break;
            }
        if (conflict)
            continue;
        status[status_cnt].last_bit_count = count_bit(row_bit[]);
        for (int j = ; j < ; j++)
            status[status_cnt].row_bit[j] = row_bit[j];
        status_cnt++;
    }
}

void work()
{
    for (int i = ; i < row_num - ; i++)
    {
        for (int j = ; j < status_cnt; j++)
        {
            int a = status[j].row_bit[];
            int b = status[j].row_bit[];
            int c = status[j].row_bit[];
            bool conflict = false;
            for (int k = ; k < ; k++)
                if (!ok(status[j].row_bit[k], i + k))
                {
                    conflict = true;
                    break;
                }
            if (conflict)
                continue;
            f[(i + ) % ][b][c] = max(f[(i + ) % ][b][c], f[i % ][a][b] + status[j].last_bit_count);
            ans = max(ans, f[(i + ) % ][b][c]);
        }
    }
}

int main()
{
    input();
    if (row_num == )
    {
        ans = ;
        for (int i = ; i < ( << col_num); i++)
        {
            if (ok(i) && ok(i, ))
                ans = max(ans, count_bit(i));
        }
        printf("%d\n", ans);
        return ;
    }
    ans = ;
    init();
    make_stat();
    work();
    printf("%d\n", ans);
    return ;
}