commit 76506c1d5fcdaf4de152016aa0fdf23b7ec81526
parent 41ab46a9750e334ef3457cfd80cff18a58009a1f
Author: Shimmy Xu <shimmy.xu@shimmy1996.com>
Date: Tue, 3 Dec 2019 11:58:28 -0500
Add Julia solution for day 03
Diffstat:
| A | day-03/day-03.jl | | | 105 | +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ |
1 file changed, 105 insertions(+), 0 deletions(-)
diff --git a/day-03/day-03.jl b/day-03/day-03.jl
@@ -0,0 +1,105 @@
+function build_path(ops)
+ path = map(ops) do op
+ steps = parse(Int, op[2:end])
+ if op[1] == 'R'
+ [steps, 0]
+ elseif op[1] == 'L'
+ [-steps, 0]
+ elseif op[1] == 'U'
+ [0, steps]
+ else
+ [0, -steps]
+ end
+ end
+ path = cumsum(path)
+ insert!(path, 1, sign.(path[1]))
+ path
+end
+
+function build_steps(ops)
+ steps = cumsum(map(op -> parse(Int, op[2:end]),ops))
+ insert!(steps, 1, 1)
+ steps
+end
+
+function get_min_intersection(p1a, p1b, p2a, p2b)
+ rotated = false
+ if p1a[1] != p1b[1]
+ p1a = [p1a[2], p1a[1]];
+ p1b = [p1b[2], p1b[1]];
+ p2a = [p2a[2], p2a[1]];
+ p2b = [p2b[2], p2b[1]];
+ rotated = true;
+ end
+ res = nothing
+ if p2a[1] == p2b[1]
+ # Parallel case.
+ if p1a[1] == p2a[1]
+ cross_start = max(p1a[2], p2a[2])
+ cross_end = min(p1b[2], p2b[2])
+ if cross_start <= cross_end
+ if cross_start * cross_end <= 0
+ res = [p1a[1], 0]
+ else
+ if abs(cross_start) <= abs(cross_end)
+ res = [p1a[1], cross_start]
+ else
+ res = [p1a[1], cross_end]
+ end
+ end
+ end
+ end
+ else
+ # Vertical case.
+ if (p1a[1] - p2a[1]) * (p1a[1] - p2b[1]) <= 0 &&
+ (p2a[2] - p1a[2]) * (p2a[2] - p1b[2]) <= 0
+ res = [p1a[1], p2a[2]]
+ end
+ end
+ if rotated && res != nothing
+ res = [res[2], res[1]]
+ end
+ res
+end
+
+function part_1(input)
+ path_1 = build_path(input[1])
+ path_2 = build_path(input[2])
+ min_dist = Inf
+ for i = 2:length(path_1)
+ for j = 2:length(path_2)
+ min_cross = get_min_intersection(path_1[i - 1], path_1[i], path_2[j - 1], path_2[j])
+ if !isnothing(min_cross)
+ min_dist = min(min_dist, sum(abs.(min_cross)))
+ end
+ end
+ end
+ Int(min_dist)
+end
+
+function part_2(input)
+ path_1 = build_path(input[1])
+ path_2 = build_path(input[2])
+ steps_1 = build_steps(input[1])
+ steps_2 = build_steps(input[2])
+ min_steps = Inf
+ for i = 2:length(path_1)
+ for j = 2:length(path_2)
+ min_cross = get_min_intersection(path_1[i - 1], path_1[i], path_2[j - 1], path_2[j])
+ if !isnothing(min_cross)
+ step_1 = steps_1[i - 1] + sum(abs.(min_cross - path_1[i - 1]))
+ step_2 = steps_2[j - 1] + sum(abs.(min_cross - path_2[j - 1]))
+ min_steps = min(min_steps, step_1 + step_2)
+ end
+ end
+ end
+ Int(min_steps)
+end
+
+input = map(readlines(open("input.txt"))) do line
+ split(strip(line), ',')
+end
+
+println("Julia:")
+println("Part 1: ", part_1(input))
+println("Part 2: ", part_2(input))