advent_of_code_2022

commit d192fc570215a53f691896191f9bb005c9119134
parent 7487d45e43c9b8d7d323a6d6befd9a5525e2aeaa
Author: Eamon Caddigan <eamon.caddigan@gmail.com>
Date:   Sun,  4 Dec 2022 03:57:53 -0800

Solution to day 3, part 1.

Diffstat:
A
src/day_3.jl
 | 
41
+++++++++++++++++++++++++++++++++++++++++

1 file changed, 41 insertions(+), 0 deletions(-)
diff --git a/src/day_3.jl b/src/day_3.jl
@@ -0,0 +1,41 @@
+#!/usr/bin/env julia
+# https://adventofcode.com/2022/day/3
+using AdventOfCode
+
+example = split("""
+    vJrwpWtwJgWrhcsFMMfFFhFp
+    jqHRNqRjqzjGDLGLrsFMfFZSrLrFZsSL
+    PmmdzqPrVvPwwTWBwg
+    wMqvLMZHhHMvwLHjbvcjnnSBnvTQFn
+    ttgJtRGJQctTZtZT
+    CrZsJsPPZsGzwwsLwLmpwMDw""",
+                "\n")
+input = readlines("data/day_3.txt")
+
+# Return a tuple of arrays for a rucksack, consisting of the priority values of
+# all of the (unique) items in the compartment. This abuses ASCII/UTF-8
+# encoding of [a-zA-Z]
+function get_compartments(rucksack)
+    rucksack = Vector{UInt8}(rucksack)
+    rucksack = map(x->(x>Int('Z')) ? x-Int('a')+1 : x-Int('A')+27,
+                   rucksack)
+    (rucksack[1:Integer(length(rucksack)/2)],
+     rucksack[Integer(length(rucksack)/2+1):end])
+end
+
+# This is written to assume there's only one item in both compartments
+function get_compartment_intersection_priority(rucksack)
+    compartments = get_compartments(rucksack)
+    intersect(compartments[1], compartments[2])[1]
+end
+
+function part_1(input)
+    sum(map(get_compartment_intersection_priority, input))
+end
+@assert part_1(example) == 157
+@info part_1(input)
+
+function part_2(input)
+    nothing
+end
+@info part_2(input)