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Day 17, Part 2: WIP
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@michaeladler
michaeladler committed Dec 20, 2023
1 parent d7aebf5 commit f7e5b9b
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Showing 2 changed files with 142 additions and 35 deletions.
175 changes: 141 additions & 34 deletions src/day17/solve.c
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Original file line number Diff line number Diff line change
Expand Up @@ -122,6 +122,61 @@ static inline int find_neighbors(int rows, int cols, Node current, Node *neighbo
return count;
}

static inline int find_neighbors_part2(int rows, int cols, Node current, Node *neighbor) {
int count = 0;
Node north = {.position = (Point2D){.x = current.position.x, .y = current.position.y - 1},
.direction = NORTH,
.direction_count = 1};
Node south = {.position = (Point2D){.x = current.position.x, .y = current.position.y + 1},
.direction = SOUTH,
.direction_count = 1};
Node east = {.position = (Point2D){.x = current.position.x + 1, .y = current.position.y},
.direction = EAST,
.direction_count = 1};
Node west = {.position = (Point2D){.x = current.position.x - 1, .y = current.position.y},
.direction = WEST,
.direction_count = 1};
switch (current.direction) {
case EAST:
if (current.direction_count >= 4) {
add_node(rows, cols, north, neighbor, &count);
add_node(rows, cols, south, neighbor, &count);
} else if (current.direction_count < 10) {
east.direction_count = current.direction_count + 1;
add_node(rows, cols, east, neighbor, &count);
}
break;
case WEST:
if (current.direction_count >= 4) {
add_node(rows, cols, north, neighbor, &count);
add_node(rows, cols, south, neighbor, &count);
} else if (current.direction_count < 10) {
west.direction_count = current.direction_count + 1;
add_node(rows, cols, west, neighbor, &count);
}
break;
case SOUTH:
if (current.direction_count >= 4) {
add_node(rows, cols, west, neighbor, &count);
add_node(rows, cols, east, neighbor, &count);
} else if (current.direction_count < 10) {
south.direction_count = current.direction_count + 1;
add_node(rows, cols, south, neighbor, &count);
}
break;
case NORTH:
if (current.direction_count >= 4) {
add_node(rows, cols, west, neighbor, &count);
add_node(rows, cols, east, neighbor, &count);
} else if (current.direction_count < 10) {
north.direction_count = current.direction_count + 1;
add_node(rows, cols, north, neighbor, &count);
}
break;
}
return count;
}

void solve(char *buf, size_t buf_size, Solution *result) {
int part1 = 0, part2 = 0;

Expand All @@ -145,47 +200,99 @@ void solve(char *buf, size_t buf_size, Solution *result) {
Node start_node_1 = {.position = start, .direction = EAST, .direction_count = 0};
Node start_node_2 = {.position = start, .direction = SOUTH, .direction_count = 0};

// Dijkstra
_cleanup_(pqu_State_free) pqu_State queue = pqu_State_init(State_compare);
pqu_State_push(&queue, (State){.node = start_node_1, .dist = 0});
pqu_State_push(&queue, (State){.node = start_node_2, .dist = 0});
// Dijkstra part 1
{
_cleanup_(pqu_State_free) pqu_State queue = pqu_State_init(State_compare);
pqu_State_push(&queue, (State){.node = start_node_1, .dist = 0});
pqu_State_push(&queue, (State){.node = start_node_2, .dist = 0});

_cleanup_(ust_NodeDistance_free) ust_NodeDistance distances =
ust_NodeDistance_init(NodeDistance_hash, NodeDistance_equal);
ust_NodeDistance_insert(&distances, (NodeDistance){.node = start_node_1, .distance = 0});
ust_NodeDistance_insert(&distances, (NodeDistance){.node = start_node_2, .distance = 0});
_cleanup_(ust_NodeDistance_free) ust_NodeDistance distances =
ust_NodeDistance_init(NodeDistance_hash, NodeDistance_equal);
ust_NodeDistance_insert(&distances, (NodeDistance){.node = start_node_1, .distance = 0});
ust_NodeDistance_insert(&distances, (NodeDistance){.node = start_node_2, .distance = 0});

// dijkstra
while (!pqu_State_empty(&queue)) {
State current = *pqu_State_top(&queue);
pqu_State_pop(&queue);
// dijkstra
while (!pqu_State_empty(&queue)) {
State current = *pqu_State_top(&queue);
pqu_State_pop(&queue);

if (Point2D_equal(&current.node.position, &dest)) {
log_debug("found destination %d,%d: %d", current.node.position.y, current.node.position.x, current.dist);
part1 = current.dist;
break;
if (Point2D_equal(&current.node.position, &dest)) {
log_debug("found destination %d,%d: %d", current.node.position.y, current.node.position.x,
current.dist);
part1 = current.dist;
break;
}

Node neighbor[3];
int neighbor_count = find_neighbors(rows, cols, current.node, neighbor);

for (int i = 0; i < neighbor_count; i++) {
Node nb = neighbor[i];
int alt = current.dist + grid[nb.position.y][nb.position.x];
NodeDistance node_distance = {.node = nb, .distance = alt};
ust_NodeDistance_node *entry = ust_NodeDistance_find(&distances, node_distance);
if (entry != NULL) {
if (entry->key.distance <= alt) {
log_debug("discarding y,x %d,%d: current best %d is better than %d", nb.position.y,
nb.position.x, entry->key.distance, alt);
continue;
}
} else {
log_debug("entry %d,%d not found in map", node_distance.node.position.y,
node_distance.node.position.x);
}
log_debug("inserting new best dist for y,x %d,%d: %d", nb.position.y, nb.position.x, alt);
ust_NodeDistance_insert(&distances, node_distance);
pqu_State_push(&queue, (State){.node = nb, .dist = alt});
}
}
}

// Dijkstra part 2
{
_cleanup_(pqu_State_free) pqu_State queue = pqu_State_init(State_compare);
pqu_State_push(&queue, (State){.node = start_node_1, .dist = 0});
pqu_State_push(&queue, (State){.node = start_node_2, .dist = 0});

_cleanup_(ust_NodeDistance_free) ust_NodeDistance distances =
ust_NodeDistance_init(NodeDistance_hash, NodeDistance_equal);
ust_NodeDistance_insert(&distances, (NodeDistance){.node = start_node_1, .distance = 0});
ust_NodeDistance_insert(&distances, (NodeDistance){.node = start_node_2, .distance = 0});

// dijkstra
while (!pqu_State_empty(&queue)) {
State current = *pqu_State_top(&queue);
pqu_State_pop(&queue);

if (Point2D_equal(&current.node.position, &dest) && current.node.direction_count >= 4) {
log_debug("found destination %d,%d: %d", current.node.position.y, current.node.position.x,
current.dist);
part2 = current.dist;
break;
}

Node neighbor[3];
int neighbor_count = find_neighbors_part2(rows, cols, current.node, neighbor);

Node neighbor[3];
int neighbor_count = find_neighbors(rows, cols, current.node, neighbor);

for (int i = 0; i < neighbor_count; i++) {
Node nb = neighbor[i];
int alt = current.dist + grid[nb.position.y][nb.position.x];
NodeDistance node_distance = {.node = nb, .distance = alt};
ust_NodeDistance_node *entry = ust_NodeDistance_find(&distances, node_distance);
if (entry != NULL) {
if (entry->key.distance <= alt) {
log_debug("discarding y,x %d,%d: current best %d is better than %d", nb.position.y, nb.position.x,
entry->key.distance, alt);
continue;
for (int i = 0; i < neighbor_count; i++) {
Node nb = neighbor[i];
int alt = current.dist + grid[nb.position.y][nb.position.x];
NodeDistance node_distance = {.node = nb, .distance = alt};
ust_NodeDistance_node *entry = ust_NodeDistance_find(&distances, node_distance);
if (entry != NULL) {
if (entry->key.distance <= alt) {
log_debug("discarding y,x %d,%d: current best %d is better than %d", nb.position.y,
nb.position.x, entry->key.distance, alt);
continue;
}
} else {
log_debug("entry %d,%d not found in map", node_distance.node.position.y,
node_distance.node.position.x);
}
} else {
log_debug("entry %d,%d not found in map", node_distance.node.position.y, node_distance.node.position.x);
log_debug("inserting new best dist for y,x %d,%d: %d", nb.position.y, nb.position.x, alt);
ust_NodeDistance_insert(&distances, node_distance);
pqu_State_push(&queue, (State){.node = nb, .dist = alt});
}
log_debug("inserting new best dist for y,x %d,%d: %d", nb.position.y, nb.position.x, alt);
ust_NodeDistance_insert(&distances, node_distance);
pqu_State_push(&queue, (State){.node = nb, .dist = alt});
}
}

Expand Down
2 changes: 1 addition & 1 deletion src/day17/solve_test.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -28,7 +28,7 @@ CTEST(day17, example) {
Solution solution;
solve(buf, strlen(buf), &solution);
ASSERT_STR("102", solution.part1);
// ASSERT_STR("0", solution.part2);
ASSERT_STR("94", solution.part2);
}

#ifdef HAVE_INPUTS
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