SpecificPolyominoCovering.cpp

#include <string>
#include <vector>
using namespace std;

class SpecificPolyominoCovering{public:
vector <string> findCovering( vector <string> region )
{
    int w = (int)region[0].size();
    int h = (int)region.size();

    for (int y=0; y<h; y++)
    for (int x=0; x<w; x++)
    {
        if (region[y][x]=='X')
        {
            if (x+1<w && region[y][x+1]=='X')
            {
                region[y][x] = '[';
                region[y][x+1] = ']';
            }
            else if (x+3<w && y+1<h &&
                region[y][x+3]=='X' &&
                region[y+1][x]=='X' &&
                region[y+1][x+1]=='X' &&
                region[y+1][x+2]=='X' &&
                region[y+1][x+3]=='X')
            {
                region[y][x] = 'A';
                region[y][x+3] = 'A';
                region[y+1][x] = 'A';
                region[y+1][x+1] = 'A';
                region[y+1][x+2] = 'A';
                region[y+1][x+3] = 'A';
            }
            else
                return vector<string>();
        }
    }

    for (int y=0; y+1<h; y++)
    for (int x=0; x+3<w; x++)
    {
        if (region[y  ][x  ]=='[' && region[y  ][x+1]==']' &&
            region[y  ][x+2]=='[' && region[y  ][x+3]==']' &&
            region[y+1][x  ]=='[' && region[y  ][x+1]==']' &&
            region[y+1][x+2]=='[' && region[y  ][x+3]==']')
        {
            region[y  ][x  ] = 'A';
            region[y  ][x+1] = 'B';
            region[y  ][x+2] = 'B';
            region[y  ][x+3] = 'A';
            region[y+1][x  ] = 'A';
            region[y+1][x+1] = 'A';
            region[y+1][x+2] = 'A';
            region[y+1][x+3] = 'A';
        }
    }

    for (int y=0; y<h; y++)
    for (int x=0; x<w; x++)
        if (region[y][x]=='[' || region[y][x]==']')
            region[y][x] = 'B';

    return region;
}};