Back

How to Construct the Graph

[Scroll to the bottom of the page to see the image this code constructs]

// See http://www.tropicalcoder.com/APermutationOnCombinatorialAlgorithms.htm

#define SCREEN_WIDTH 1152
#define SCREEN_HEIGHT 640


LPPOINT leftBranch(LPPOINT p, int length)
{
 int x = p->x;
 int y = p->y;
 
 for(int i = 0; i < length; i++)
 {
     --x; --y;
     if(x == 0)return NULL;
     if(y == 0)return NULL;
     putColour(x, y, 0x0040FF40);
 }
 p->x = x;
 p->y = y;
 return p;
}


LPPOINT rightBranch(LPPOINT p, int length)
{
 int x = p->x;
 int y = p->y;
 
 for(int i = 0; i < length; i++)
 {
     ++x; --y;
     if(x == SCREEN_WIDTH)return NULL;
     if(y == 0)return NULL;
     putColour(x, y, 0x0040FF40);
 }
 p->x = x;
 p->y = y;
 return p;
}


void recurseBranches(int x, int y, int length)
{
 POINT point, *p;
 
 point.x = x;
 point.y = y;
 p = leftBranch(&point, length);
 if(p != NULL)
 {
    if((length >> 1) != 0)
    {
        recurseBranches(p->x, p->y, length >> 1);
    }
 }


 point.x = x;
 point.y = y;
 p = rightBranch(&point, length);
 if(p != NULL)
 {
    if((length >> 1) != 0)
    {
        recurseBranches(p->x, p->y, length >> 1);
    }
 }
}


void __cdecl thread(void *pv)
{
 RECT rect;
 int x, y;
 
 x = SCREEN_WIDTH / 2;
 y = SCREEN_HEIGHT - 64;
 putColour(x, y, 0x0040FF40);
 recurseBranches(x, y, 256);
 
 GetClientRect(hWnd, &rect);
 InvalidateRect(hWnd, &rect, false);
 UpdateWindow(hWnd);
 bThreadLive = false;
}

This is the image produced by the code shown.

Your comments are welcome.