CC150 5.8

5_8.cpp

/* CC150 5.8
 * Implement a function drawHorizontalLine(byte[] screen, int width, int x1, int x2, int y)
 * which draws a horizontal line from (x1, y) to (x2, y).
 */

#include <iostream>
#include <vector>

using namespace std;

void drawHorizontalLine(vector<unsigned char> &screen, int width, int x1, int x2, int y)
{
	if (x1 > x2 || x1 < 0 || x1 >= width || x2 < 0 || x2 >= width) // invalid x coordinates
		return;
	int height = screen.size() / width * 8;
	if (y < 0 || y >= height) // invalid y coordinate
		return;
	int pixStart = y * width + x1;
	int pixEnd = y * width + x2;
	for (int byte = pixStart / 8; byte != pixEnd / 8; ++byte)
		screen[byte] |= 0xFF; // roughly draw the line
	screen[pixStart / 8] &= (0xFF >> (pixStart % 8)); // clear the leading pixels
	screen[pixEnd / 8] |= ~(0xFF >> (pixEnd % 8 + 1)); // fill the tailing pixels
	return;
}

void display(vector<unsigned char> screen, int width)
{
	int count = 0;
	for (auto byte : screen) {
		for (int k = 7; k >= 0; --k)
			cout << ((byte & (1 << k)) >> k);
		count += 8;
		if (count % width == 0)
			cout << endl;
	}
	cout << endl;
}

int main()
{
	vector<unsigned char> screen(64, 0x00); // 32 * 16
	int width = 32;
	int x1, x2, y;
	while (cin >> x1 >> x2 >> y) { // support multiple inputs
		drawHorizontalLine(screen, width, x1, x2, y);
		display(screen, width);
	}
	return 0;
}