From 4c58e5c51cecfdd4509b927a048b60f755a58e7c Mon Sep 17 00:00:00 2001
From: Parnic <github@parnic.com>
Date: Sun, 26 Jun 2022 10:24:54 -0500
Subject: [PATCH] Day 24 part 1

I think I understand part 2, I just...ugh. It seems like it's going to be a beating of rote map implementation.
---
 days/24.go      | 128 ++++++++++++++++++++++++++++++++++++++++++++++++
 inputs/24p.txt  |   5 ++
 inputs/24s1.txt |   5 ++
 inputs/24s2.txt |   5 ++
 main.go         |   1 +
 5 files changed, 144 insertions(+)
 create mode 100644 days/24.go
 create mode 100644 inputs/24p.txt
 create mode 100644 inputs/24s1.txt
 create mode 100644 inputs/24s2.txt

diff --git a/days/24.go b/days/24.go
new file mode 100644
index 0000000..84b74d9
--- /dev/null
+++ b/days/24.go
@@ -0,0 +1,128 @@
+package days
+
+import (
+	"fmt"
+	"math"
+
+	u "parnic.com/aoc2019/utilities"
+)
+
+var (
+	day24AdjacentOffsets = []u.Vec2i{
+		{X: -1, Y: 0},
+		{X: 1, Y: 0},
+		{X: 0, Y: -1},
+		{X: 0, Y: 1},
+	}
+)
+
+type Day24 struct {
+	grid [][]bool
+}
+
+func (d *Day24) Parse() {
+	lines := u.GetStringLines("24p")
+	d.grid = make([][]bool, len(lines))
+	for i, line := range lines {
+		d.grid[i] = make([]bool, len(line))
+		for j, ch := range line {
+			d.grid[i][j] = ch == '#'
+		}
+	}
+}
+
+func (d Day24) Num() int {
+	return 24
+}
+
+func (d Day24) calcActivatedNeighbors(grid [][]bool, i, j int) int {
+	activatedNeighbors := 0
+	for _, o := range day24AdjacentOffsets {
+		newI := i + o.X
+		newJ := j + o.Y
+		if newI < 0 || newI >= len(grid) || newJ < 0 || newJ >= len(grid[i]) {
+			continue
+		}
+		if grid[newI][newJ] {
+			activatedNeighbors++
+		}
+	}
+
+	return activatedNeighbors
+}
+
+func (d Day24) calcRating(grid [][]bool) int {
+	rating := 0
+	for i, r := range grid {
+		for j := range r {
+			pow := (i * len(r)) + j
+			if grid[i][j] {
+				result := int(math.Pow(2, float64(pow)))
+				rating += result
+			}
+		}
+	}
+	return rating
+}
+
+func copy2d[T comparable](dest [][]T, src [][]T) {
+	for i, r := range src {
+		copy(dest[i], r)
+	}
+}
+
+func (d Day24) Draw(grid [][]bool) {
+	for _, r := range grid {
+		for _, c := range r {
+			if c {
+				fmt.Print("#")
+			} else {
+				fmt.Print(".")
+			}
+		}
+		fmt.Println()
+	}
+	fmt.Println()
+}
+
+func (d *Day24) Part1() string {
+	grid := make([][]bool, len(d.grid))
+	scratch := make([][]bool, len(grid))
+	for i, g := range d.grid {
+		grid[i] = make([]bool, len(g))
+		scratch[i] = make([]bool, len(g))
+		copy(grid[i], d.grid[i])
+	}
+
+	found := false
+	answer := 0
+	seenRatings := make([]int, 0)
+	for i := 1; !found; i++ {
+		// d.Draw(grid)
+		for i, r := range grid {
+			for j := range r {
+				numActivated := d.calcActivatedNeighbors(grid, i, j)
+				if grid[i][j] {
+					scratch[i][j] = numActivated == 1
+				} else {
+					scratch[i][j] = numActivated == 1 || numActivated == 2
+				}
+			}
+		}
+
+		rating := d.calcRating(scratch)
+		if u.ArrayContains(seenRatings, rating) {
+			found = true
+			d.Draw(scratch)
+			answer = rating
+		}
+		seenRatings = append(seenRatings, rating)
+		copy2d(grid, scratch)
+	}
+
+	return fmt.Sprintf("First repeated biodiversity rating is %s%d%s", u.TextBold, answer, u.TextReset)
+}
+
+func (d *Day24) Part2() string {
+	return fmt.Sprintf("%s%d%s", u.TextBold, 0, u.TextReset)
+}
diff --git a/inputs/24p.txt b/inputs/24p.txt
new file mode 100644
index 0000000..3406c57
--- /dev/null
+++ b/inputs/24p.txt
@@ -0,0 +1,5 @@
+##..#
+...##
+.#.##
+#..#.
+..#..
\ No newline at end of file
diff --git a/inputs/24s1.txt b/inputs/24s1.txt
new file mode 100644
index 0000000..949fe7c
--- /dev/null
+++ b/inputs/24s1.txt
@@ -0,0 +1,5 @@
+....#
+#..#.
+#..##
+..#..
+#....
\ No newline at end of file
diff --git a/inputs/24s2.txt b/inputs/24s2.txt
new file mode 100644
index 0000000..b95bc74
--- /dev/null
+++ b/inputs/24s2.txt
@@ -0,0 +1,5 @@
+.....
+.....
+.....
+#....
+.#...
\ No newline at end of file
diff --git a/main.go b/main.go
index 9564d8e..8f04338 100644
--- a/main.go
+++ b/main.go
@@ -57,6 +57,7 @@ var dayMap = []day{
 	&days.Day21{},
 	&days.Day22{},
 	&days.Day23{},
+	&days.Day24{},
 }
 
 func main() {