59 lines
1.9 KiB
C
59 lines
1.9 KiB
C
#include "pq.h"
|
|
#include "prim.h"
|
|
#include "set.h"
|
|
|
|
typedef struct {
|
|
size_t x, y;
|
|
mazeedge_dir_t dir;
|
|
} _point_t;
|
|
|
|
DEFINE_PQ(_point_t, PointPQ, unsigned int);
|
|
|
|
void prim(mazegrid_t const* g, mazegrid_t* result) {
|
|
NEW_PQ_SZ(PointPQ, q, g->width*g->height*4);
|
|
struct node_set* s = node_set_new(g->width, g->height);
|
|
*result = mazegrid_new(g->width, g->height);
|
|
|
|
node_set_add(s, 0, 0);
|
|
if (g->height > 1) {
|
|
_point_t e = { 0, 1, EDGE_DOWN };
|
|
PUSH_PQ(q, PointPQ, e, mazegrid_get_edge(g, 0, 0, EDGE_UP));
|
|
}
|
|
if (g->width > 1) {
|
|
_point_t e = { 1, 0, EDGE_LEFT };
|
|
PUSH_PQ(q, PointPQ, e, mazegrid_get_edge(g, 0, 0, EDGE_RIGHT));
|
|
}
|
|
while (!EMPTY_PQ(q) && (node_set_size(s) < g->width * g->height)) {
|
|
_point_t e;
|
|
unsigned int p;
|
|
POP_PQ(q, PointPQ, e, p);
|
|
if (node_set_contains(s, e.x, e.y)) continue;
|
|
|
|
// add edge to tree
|
|
mazegrid_set_edge(result, e.x, e.y, e.dir, 1);
|
|
|
|
// add neighbors
|
|
if ((e.x > 0) && !node_set_contains(s, e.x - 1, e.y)) {
|
|
_point_t pt = { e.x - 1, e.y, EDGE_RIGHT };
|
|
PUSH_PQ(q, PointPQ, pt, mazegrid_get_edge(g, e.x, e.y, EDGE_LEFT));
|
|
}
|
|
if ((e.x < g->width - 1) && !node_set_contains(s, e.x + 1, e.y)) {
|
|
_point_t pt = { e.x + 1, e.y, EDGE_LEFT };
|
|
PUSH_PQ(q, PointPQ, pt, mazegrid_get_edge(g, e.x, e.y, EDGE_LEFT));
|
|
}
|
|
if ((e.y > 0) && !node_set_contains(s, e.x, e.y - 1)) {
|
|
_point_t pt = { e.x, e.y - 1, EDGE_UP };
|
|
PUSH_PQ(q, PointPQ, pt, mazegrid_get_edge(g, e.x, e.y, EDGE_DOWN));
|
|
}
|
|
if ((e.y < g->height - 1) && !node_set_contains(s, e.x, e.y + 1)) {
|
|
_point_t pt = { e.x, e.y + 1, EDGE_DOWN };
|
|
PUSH_PQ(q, PointPQ, pt, mazegrid_get_edge(g, e.x, e.y, EDGE_UP));
|
|
}
|
|
|
|
node_set_add(s, e.x, e.y);
|
|
}
|
|
|
|
node_set_free(s);
|
|
FREE_PQ(q);
|
|
}
|