gistfile1.c

#include <stdio.h>
#include <stdlib.h>


#define NROWS 5
#define NCOLS 5

/* The array I'll be walking through */
int array2d[NROWS][NCOLS] = {{1,2,3,4,5},
			     {6,7,8,9,10},
			     {11,12,13,14,15},
			     {16,17,18,19,20},
			     {21,22,23,24,25}};

struct Node
{
  int row;
  int col;
  struct Node* direction[4];
};

int nodetotal = 0;

struct Node* initNode()
{
  printf("Making node %i\n", nodetotal++);
  struct Node *tmp = (struct Node *)malloc(sizeof(struct Node));
  tmp->direction[0] = NULL;
  tmp->direction[1] = NULL;
  tmp->direction[2] = NULL;
  tmp->direction[3] = NULL;
  return tmp;

}

int oppDirection(int direction)
{
  /* Returns the opposite direction
     eg. North returns South, West
     returns East, etc. */
  if (direction == 0) {return 2;}
  else if (direction == 1) {return 4;}
  else if (direction == 2) {return 0;}
  else if (direction == 3) {return 1;}
}

int limiter = 0;

void walk(struct Node *node)
{
  //if (++limiter > 5) {return;}
  struct Node *nextnode;
  printf("Starting walk %i\n", limiter++);
  printf("Row: %i Col: %i, Memory: %p\n", node->row, node->col, node);

  /* Look to see if North is a legit direction and unvisited */
  if ((node->row != 0) && (node->direction[0] == 0))
    {
      printf("North is clear\n");
      nextnode = initNode();
      nextnode->row = node->row - 1;
      nextnode->col = node->col;
      /* The next node's South is the current node */
      nextnode->direction[2] = node;
      /* The current node's North is the newly created node */
      node->direction[0] = nextnode;
      printf("Taking a walk North\n");
      walk(nextnode);
    }

  /* Look to see if East is a legit direction and unvisited */
  if ((node->col < NCOLS - 1) && (node->direction[1] == 0))
    {
      printf("East is clear\n");
      nextnode = initNode();
      nextnode->col = node->col + 1;
      nextnode->row = node->row;
      /* The next node's West is the current node */
      nextnode->direction[3] = node;
      /* The current node's East is the newly created node */
      node->direction[1] = nextnode;
      walk(nextnode);
    }
  
  /* Look to see if South is a legit direction and unvisited */
  if ((node->row < NROWS - 1) && (node->direction[2] == 0))
    {
      printf("South is clear\n");
      nextnode = initNode();
      nextnode->row = node->row + 1;
      nextnode->col = node->col;
      /* The next node's North is the current node */
      nextnode->direction[0] = node;
      /* The current node's South is the newly created node */
      node->direction[2] = nextnode;
      walk(nextnode);
    }
  
  /* Look to see if West is a legit direction and unvisited */
  if ((node->col != 0) && (node->direction[3] == 0))
    {
      printf("West is clear\n");
      nextnode = initNode();
      nextnode->col = node->col - 1;
      nextnode->row = node->row;
      /* The next node's East is the current node */
      nextnode->direction[1] = node;
      /* The current node's West is the newly created node */
      node->direction[3] = nextnode;
      walk(nextnode);
    }


  return;
}

int main(int argc, char *argv)
{
  /* Here's our starting point at 0,0 */
  struct Node *head = initNode();
  head->row = 0;
  head->col = 0;

  /* No freeing memory yet... I'll figure that out... */

  walk(head);

  return 0;
}