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check cost validity before entering in pq

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Felix Van der Jeugt 2021-12-15 11:30:14 +01:00
parent 8fe19e4643
commit e5d2beb9e0
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1 changed files with 8 additions and 10 deletions
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18
day15/part2.lua
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@ -33,16 +33,14 @@ local distances = {}
local n = { 1, 1, 0 }
while n ~= nil and (distances[5*h] == nil or distances[5*h][5*w] == nil) do
local r, c, d = unpack(n)
if cost(r, c) < math.huge then
local row = distances[r] or {}
if d < (row[c] or math.huge) then
row[c] = d
distances[r] = row
pq:add({ r-1, c, d + cost(r-1, c) })
pq:add({ r, c-1, d + cost(r, c-1) })
pq:add({ r+1, c, d + cost(r+1, c) })
pq:add({ r, c+1, d + cost(r, c+1) })
end
local row = distances[r] or {}
if d < (row[c] or math.huge) then
row[c] = d
distances[r] = row
if cost(r-1, c) < math.huge then pq:add({ r-1, c, d + cost(r-1, c) }) end
if cost(r, c-1) < math.huge then pq:add({ r, c-1, d + cost(r, c-1) }) end
if cost(r+1, c) < math.huge then pq:add({ r+1, c, d + cost(r+1, c) }) end
if cost(r, c+1) < math.huge then pq:add({ r, c+1, d + cost(r, c+1) }) end
end
n = pq:pop()
end