Day 8 solution

I had fun with this one. I liked how straightforward it was, and it's always satisfying to see the code print a message visually when you're done.

days/08.go

@@ -0,0 +1,102 @@
+package days
+
+import (
+	"fmt"
+	"math"
+	"strings"
+
+	"parnic.com/aoc2019/utilities"
+)
+
+type Day08 struct {
+	img [][]int
+}
+
+const (
+	imgWidth  = 25
+	imgHeight = 6
+)
+
+func (d *Day08) Parse() {
+	contents := utilities.GetStringContents("08p")
+	imgSize := imgWidth * imgHeight
+	layers := len(contents) / imgSize
+	d.img = make([][]int, layers)
+	for layer := 0; layer < layers; layer++ {
+		d.img[layer] = make([]int, imgSize)
+		for i := 0; i < imgSize; i++ {
+			d.img[layer][i] = int(contents[(layer*imgSize)+i] - '0')
+		}
+	}
+}
+
+func (d Day08) Num() int {
+	return 8
+}
+
+func (d *Day08) Part1() string {
+	fewestZeroes := math.MaxInt
+	var layerFewestZeroes int
+	for layer := range d.img {
+		zeroes := 0
+		for i := range d.img[layer] {
+			if d.img[layer][i] == 0 {
+				zeroes++
+			}
+		}
+
+		if zeroes < fewestZeroes {
+			fewestZeroes = zeroes
+			layerFewestZeroes = layer
+		}
+	}
+
+	numOne := 0
+	numTwo := 0
+	for i := range d.img[layerFewestZeroes] {
+		if d.img[layerFewestZeroes][i] == 1 {
+			numOne++
+		} else if d.img[layerFewestZeroes][i] == 2 {
+			numTwo++
+		}
+	}
+
+	return fmt.Sprintf("Fewest zeroes on layer %d, #1s * #2s = %d * %d = %s%d%s",
+		layerFewestZeroes,
+		numOne,
+		numTwo,
+		utilities.TextBold,
+		numOne*numTwo,
+		utilities.TextReset,
+	)
+}
+
+func (d *Day08) Part2() string {
+	imgSize := imgWidth * imgHeight
+	finalImg := make([]int, imgSize)
+	for i := 0; i < imgSize; i++ {
+		for layer := 0; layer < len(d.img); layer++ {
+			if d.img[layer][i] != 2 {
+				finalImg[i] = d.img[layer][i]
+				break
+			}
+		}
+	}
+
+	outStr := strings.Builder{}
+	outStr.WriteString("Message received:\n")
+	outStr.WriteString(utilities.TextBold)
+	for y := 0; y < imgHeight; y++ {
+		for x := 0; x < imgWidth; x++ {
+			if finalImg[(y*imgWidth)+x] == 0 {
+				outStr.WriteRune(' ')
+			} else {
+				outStr.WriteRune('█')
+			}
+		}
+		outStr.WriteRune('\n')
+	}
+	outStr.WriteString(utilities.TextReset)
+
+	return outStr.String()
+}

inputs/08s1.txt

@@ -0,0 +1 @@
+123456789012

main.go

@@ -38,6 +38,7 @@ var dayMap = []day{
 	&days.Day05{},
 	&days.Day06{},
 	&days.Day07{},
+	&days.Day08{},
 }
 
 func main() {