CareerCup

If I understand correctly, Bitmap class is supposed to provide a diff(Btimap other) method that should output the diff?

Also, is the goal to minimize number of changed/removed/added bits in the diff?
For example, given two bitmaps {0,1,0,1,0,1} and {1,0,1,0,1,0}, should the diff be <Added: {0}, Removed: {5}> or <Changed {0-5}>?

#include <vector>
using namespace std;

class ResizableBitmap
{
  int iWidth, iHeight;
  vector<unsigned char> vPixels;
  vector<bool> vMask;

  void ResizeVectors()
  {
	  vPixels.resize(3 * iWidth * iHeight);
	  vMask.resize(3 * iWidth * iHeight);
  }

public:

  ResizableBitmap()
{
	iWidth = 640;
	iHeight = 480;
	ResizeVectors();
}

  ResizableBitmap(int& iW, int& iH)
  {
	  iWidth = iW;
	  iHeight = iH;
	  ResizeVectors();
  }

  ~ResizableBitmap()
  {
	  vPixels.clear();
	  vMask.clear();
  }

  void CompareWithPreviousBitmap(const ResizableBitmap& PreviousBitmap);
  void SomeOperation();
};

void ResizableBitmap::CompareWithPreviousBitmap(const ResizableBitmap& PreviousBitmap)
{
	unsigned int i;

	// There can be 2 cases:
	// 1). Size is changed - the places that were added or substracted - are different
	// 2). Size is the same - each pixel is compared with the previous one by "XOR"
	if (PreviousBitmap.iWidth < iWidth)
	{
		// mark the new bitmap fragment as changed
	}

	if (PreviousBitmap.iHeight < iHeight)
	{
		// mark the new bitmap fragment as changed
	}

	if ((PreviousBitmap.iWidth == iWidth) && (PreviousBitmap.iHeight == iHeight))
	{
		for (i = 0; i < vPixels.size(); i++)
		{
			vMask[i] = (bool)(vPixels[i] ^ PreviousBitmap.vPixels[i]);
		}
	}
}

void ResizableBitmap::SomeOperation()
{
	unsigned int i;

	for (i = 0; i < vPixels.size(); i++)
	{
		if (vMask[i])
		{
			// do something only if the pixel is different than the previous one
		}
	}
}