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Optimize day 15 solution by using priority queue
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Pascal Lais
2021-12-16 16:48:45 +01:00
parent c365cc5b64
commit d16807f80d
1 changed files with 11 additions and 16 deletions
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day-15/day-15.py
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@@ -1,5 +1,6 @@
#!/usr/bin/env python3 #!/usr/bin/env python3
from pathlib import Path from pathlib import Path
from heapq import heappush, heappop
def part_1(input): def part_1(input):
@@ -11,16 +12,13 @@ def part_1(input):
start = (0, 0) start = (0, 0)
end = (x_size - 1, y_size - 1) end = (x_size - 1, y_size - 1)
cost = {start: 0} cost = {start: 0}
queue = set([start]) queue = [(0, start)]
done = set() done = set()
neighbors = set([(-1, 0), (0, -1), (0, 1), (1, 0)]) neighbors = set([(-1, 0), (0, -1), (0, 1), (1, 0)])
while len(queue): while len(queue):
cur_cost = None cur_cost, current = heappop(queue)
for n in queue: if current in done:
if cur_cost == None or cost[n] < cur_cost: continue
cur_cost = cost[n]
current = n
queue.remove(current)
(xc, yc) = current (xc, yc) = current
next = set() next = set()
for (xn, yn) in neighbors: for (xn, yn) in neighbors:
@@ -31,7 +29,7 @@ def part_1(input):
next_cost = cur_cost + nodes[n] next_cost = cur_cost + nodes[n]
if not n in cost or next_cost < cost[n]: if not n in cost or next_cost < cost[n]:
cost[n] = next_cost cost[n] = next_cost
queue.add(n) heappush(queue, (next_cost, n))
done.add(current) done.add(current)
result = cost[end] result = cost[end]
print("Part 1 result:", result) print("Part 1 result:", result)
@@ -47,16 +45,13 @@ def part_2(input):
start = (0, 0) start = (0, 0)
end = ((x_size * repeat) - 1, (y_size * repeat) - 1) end = ((x_size * repeat) - 1, (y_size * repeat) - 1)
cost = {start: 0} cost = {start: 0}
queue = set([start]) queue = [(0, start)]
done = set() done = set()
neighbors = set([(-1, 0), (0, -1), (0, 1), (1, 0)]) neighbors = set([(-1, 0), (0, -1), (0, 1), (1, 0)])
while len(queue): while len(queue):
cur_cost = None cur_cost, current = heappop(queue)
for n in queue: if current in done:
if cur_cost == None or cost[n] < cur_cost: continue
cur_cost = cost[n]
current = n
queue.remove(current)
(xc, yc) = current (xc, yc) = current
next = set() next = set()
for (xn, yn) in neighbors: for (xn, yn) in neighbors:
@@ -72,7 +67,7 @@ def part_2(input):
next_cost -= 9 next_cost -= 9
if not (x, y) in cost or (cur_cost + next_cost) < cost[(x, y)]: if not (x, y) in cost or (cur_cost + next_cost) < cost[(x, y)]:
cost[(x, y)] = cur_cost + next_cost cost[(x, y)] = cur_cost + next_cost
queue.add((x, y)) heappush(queue, (cur_cost + next_cost, (x, y)))
done.add(current) done.add(current)
result = cost[end] result = cost[end]
print("Part 2 result:", result) print("Part 2 result:", result)