62 lines
1.2 KiB
Julia
62 lines
1.2 KiB
Julia
include(joinpath(readchomp(`git rev-parse --show-toplevel`), "aoc.jl"))
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import .Aoc: @aoc
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using Pipe: @pipe
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using Combinatorics
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function lowpoints(map)
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low = Dict()
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for x in 1:length(map)
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for y in 1:length(map[1])
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adjacent = []
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for (i,j) in [ [x+i,y+j] for (i,j) in zip([0,1,0,-1], [1,0,-1,0]) ]
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if i in 1:length(map) && j in 1:length(map[1])
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push!(adjacent, map[i][j])
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end
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end
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if map[x][y] < minimum(adjacent)
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low[[x,y]] = map[x][y]
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end
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end
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end
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return low
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end
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function p1(input::Vector{String})
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map = [ parse.(Int, collect(l)) for l in input ]
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low = lowpoints(map)
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return sum(values(low)) + length(low)
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end
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function search(map, pos)
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q = [pos]
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v = [pos]
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while length(q) > 0
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c = popfirst!(q)
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h = map[c[1]][c[2]]
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for p in [ [c[1]+i,c[2]+j] for (i,j) in zip([0,1,0,-1], [1,0,-1,0]) ]
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if p[1] in 1:length(map) && p[2] in 1:length(map[1])
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if p ∉ v
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h2 = map[p[1]][p[2]]
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if h < h2 < 9
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push!(v, p)
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push!(q, p)
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end
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end
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end
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end
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end
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return v
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end
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function p2(input::Vector{String})
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map = [ parse.(Int, collect(l)) for l in input ]
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low = lowpoints(map)
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basin_sizes = [ length(search(map, p)) for p in keys(low) ]
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return prod(sort(basin_sizes)[end-2:end])
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end
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@aoc(2021, 9)
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