POJ-3279 (Fliptile )

最新推荐文章于 2021-07-06 00:06:22 发布

原创最新推荐文章于 2021-07-06 00:06:22 发布 · 275 阅读

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POJ-3279

#include <iostream>
#include <cstdio>
#include <cstring>

using namespace std;

const int MAXN = 20;
int res[MAXN][MAXN];
int tmp[MAXN][MAXN];
int state[MAXN][MAXN];
int grid[MAXN][MAXN];

int n, m;
int ans;
const int INF = 0x3f3f3f;
int dist[5][2] = {{1, 0}, {-1, 0}, {0, 1}, {0, -1}, {0, 0}};
void flip(int x, int y){
    tmp[x][y] = 1;
    for(int i = 0; i < 5; ++i)
    {
        int dx = x + dist[i][0], dy = y + dist[i][1];
        state[dx][dy] = !state[dx][dy];
     }
}

bool isEmpty(int n)
{
    for(int i = 1; i <= m; ++i)
    {
        if(state[n][i] == 1) return false; 
    }
    return true;
}

void solve(int s)
{
    memcpy(state, grid, sizeof(grid));
    memset(tmp, 0, sizeof(tmp));

    int cnt = 0;
    for(int i = 0; i < m; ++i)
    {
        if((s >> i) & 1)
        {
            flip(1, i + 1);
            cnt ++;
        }
    }

    for(int i = 2; i <= n; ++i)
    {
        for(int j = 1; j <= m; ++j)
        {
            if(state[i - 1][j] == 1)
            {
                flip(i, j);
                cnt ++;
            }
        }
    }

    if(isEmpty(n) && cnt < ans)
    {
        ans = cnt;
        memcpy(res, tmp, sizeof(tmp));
    }
}
int main()
{
    while(cin >> n >> m)
    {
        for(int i = 1; i <= n; ++i)
        {
            for(int j = 1; j <= m; ++j)
            {
                cin >> grid[i][j];
            }
         } 

        ans = INF;
        int t = 1 << m;

        for(int i = 0; i < t; ++i)
        {
            solve(i);
        }

        if(ans == INF) printf("IMPOSSIBLE\n");
        else{
            for(int i = 1; i <= n; ++i) 
            {
                for(int j = 1; j <= m; ++j)
                {
                    printf("%d%c", res[i][j], j == m ? '\n' : ' ');
                }
            }
        }
    }

    return 0;
}