[Julia] day 11

inputs/11_example.txt

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+...#......
+.......#..
+#.........
+..........
+......#...
+.#........
+.........#
+..........
+.......#..
+#...#.....

solutions/11_example.txt

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+374
+82000210

solutions/11_moelf.txt

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+9795148
+650672493820

src/julia/11_moelf.jl

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+const CI = CartesianIndex
+cityblock(a::CI, b::CI) = sum(abs, Tuple(a-b))
+
+function impl(MAP, exp_const)
+    galaxies = findall(==('#'), MAP)
+    N = exp_const - 1
+    for (i, j) in zip(axes(MAP, 1), axes(MAP, 2))
+        if all(==('.'), @view MAP[i, :])
+            mask = findall(c -> c[1] < i, galaxies)
+            galaxies[mask] .-= CI(N, 0)
+        end
+
+        if all(==('.'), @view MAP[:, j])
+            mask = findall(c -> c[2] < j, galaxies)
+            galaxies[mask] .-= CI(0, N)
+        end
+    end
+
+    res = 0
+    for i in eachindex(galaxies), j in i+1:lastindex(galaxies)
+        res += cityblock(galaxies[i], galaxies[j])
+    end
+
+    res
+end
+
+function main(path)
+    MAP = stack(readlines(path); dims=1)
+    println(impl(MAP, 2))
+    println(impl(MAP, 1000000))
+end
+
+(abspath(PROGRAM_FILE) == @__FILE__) && main(ARGS[1])