Jackson Day 9, Part 1, Part 2 (#41)

* Jackson Day 8, Part 1, Part 2

* Jackson Day 9, Part 1, Part 2

* Remove part-2 split

* Remove mutable diff array

2023/09/jacksonmowry.v

@@ -0,0 +1,30 @@
+module main
+
+import os
+import arrays
+
+fn main() {
+	mut forward := 0
+	mut backward := 0
+
+	lines := os.read_lines('mirage_maintenance.input')!.map(it.split(' ').map(it.int()))
+
+	for line in lines {
+		front, back := next_value(line)
+		backward += front
+		forward += back
+	}
+	println('Part 1: ${forward}')
+	println('Part 2: ${backward}')
+}
+
+fn next_value(input []int) (int, int) {
+	if input.all(it == 0) {
+		return 0, 0
+	}
+	diffs := arrays.flat_map_indexed[int, int](input, fn [input] (i int, e int) []int {
+		return [input[i + 1] or { return [] } - input[i]]
+	})
+	front, back := next_value(diffs)
+	return input.first() - front, input.last() + back
+}

2023/09/mirage_maintenance.input

@@ -0,0 +1,3 @@
+0 3 6 9 12 15
+1 3 6 10 15 21
+10 13 16 21 30 45

known_outputs/2023/09/jacksonmowry.out

@@ -0,0 +1,2 @@
+Part 1: 114
+Part 2: 2