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