87 lines
2.3 KiB
Julia
87 lines
2.3 KiB
Julia
include("utils.jl")
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function parse_input(filename)
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map(x->parse.(Int, x), split.(non_empty_lines(filename), ""))
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end
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function sink_locations(width, height, heights)
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sinks = []
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for x in 1:width
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for y in 1:height
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minimum = true
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if x > 1
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minimum &= heights[x - 1, y] > heights[x, y]
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end
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if x < width
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minimum &= heights[x + 1, y] > heights[x, y]
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end
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if y > 1
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minimum &= heights[x, y - 1] > heights[x, y]
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end
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if y < height
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minimum &= heights[x, y + 1] > heights[x, y]
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end
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if minimum
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push!(sinks, (x, y))
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end
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end
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end
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sinks
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end
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function solution9_1()
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input = collect(parse_input("9_ex.data"))
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width = length(input[1])
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height = length(input)
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heights = reshape(reduce(vcat, input),(width,height))
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sinks = sink_locations(width, height, heights)
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risk = 0
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for sink in sinks
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risk += heights[sink[1], sink[2]] + 1
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end
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risk
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end
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function basin_size(x, y, width, height, heights)
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heights = copy(heights)
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to_visit = [CartesianIndex(x, y)]
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visited = []
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while length(to_visit) > 0
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current = pop!(to_visit)
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if current in visited
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continue
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end
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push!(visited, current)
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if heights[current] == 9
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continue
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end
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if current[1] > 1
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push!(to_visit, CartesianIndex(-1, 0) + current)
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end
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if current[1] < width
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push!(to_visit, CartesianIndex(+1, 0) + current)
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end
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if current[2] > 1
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push!(to_visit, CartesianIndex(0, -1) + current)
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end
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if current[2] < height
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push!(to_visit, CartesianIndex(0, +1) + current)
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end
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heights[current] = -1
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end
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length(filter(==(-1), heights))
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end
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function solution9_2()
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input = collect(parse_input("9.data"))
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width = length(input[1])
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height = length(input)
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heights = reshape(reduce(vcat, input),(width,height))
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sizes = map(sink_locations(width, height, heights)) do sink
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size = basin_size(sink[1], sink[2], width, height, heights)
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end
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reduce(*, Iterators.take(reverse(sort(sizes)), 3))
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end
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solution9_2()
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