feat(2024): add day 3

go/2024/README.md

@@ -16,15 +16,17 @@ Collect stars by solving puzzles. Two puzzles will be made available on each day
 | ----------------------------------------------------------------------------------------------------------------- | --- | --------: | --- | --------: |
 | [Day 1: Historian Hysteria](https://github.com/believer/advent-of-code/blob/master/go/2024/puzzles/day01/main.go) | 🌟  |   1666427 | 🌟  |  24316233 |
 | [Day 2: Red-Nosed Reports](https://github.com/believer/advent-of-code/blob/master/go/2024/puzzles/day02/main.go)  | 🌟  |       564 | 🌟  |       604 |
+| [Day 3: Mull It Over](https://github.com/believer/advent-of-code/blob/master/go/2024/puzzles/day03/main.go)       | 🌟  | 161085926 | 🌟  |  82045421 |
 
 ## Benchmarks
 
 Using Go's built-in benchmarking with the [testing](https://pkg.go.dev/testing#hdr-Benchmarks) package. Computer is a 2021 MacBook Pro M1 Pro, 32 GB RAM.
 
-| Day |           #1 |           #2 | Improvement\*      |
-| --- | -----------: | -----------: | ------------------ |
-| 1   | 116264 ns/op | 131233 ns/op | `3,53%` / `68,43%` |
-| 2   | 310935 ns/op | 723512 ns/op |                    |
+| Day |           #1 |            #2 | Improvement\*      |
+| --- | -----------: | ------------: | ------------------ |
+| 1   | 116264 ns/op |  131233 ns/op | `3,53%` / `68,43%` |
+| 2   | 310935 ns/op |  723512 ns/op |                    |
+| 3   | 336448 ns/op | 1246155 ns/op |                    |
 
 \* compared to first solution
 

go/2024/puzzles/day03/main.go

@@ -0,0 +1,64 @@
+package main
+
+import (
+	"fmt"
+	"regexp"
+	"strings"
+
+	"github.com/believer/aoc-2024/utils"
+	"github.com/believer/aoc-2024/utils/files"
+)
+
+// Wasted a couple of minutes when I didn't see that the test input had
+// changed for part two and was wondering why my regex didn't find do's and don'ts...
+
+// There might be something clever we can do here instead of the regexes?
+func main() {
+	fmt.Println("Part 1: ", part1("input.txt"))
+	fmt.Println("Part 2: ", part2("input.txt"))
+}
+
+func part1(name string) int {
+	program := files.Read(name)
+	re := regexp.MustCompile(`mul\(\d{1,3},\d{1,3}\)`)
+	matches := re.FindAllString(program, -1)
+	total := 0
+
+	for _, mul := range matches {
+		parts := strings.Split(mul, ",")
+		lhs := utils.MustIntFromString(parts[0][4:])
+		rhs := utils.MustIntFromString(parts[1][:len(parts[1])-1])
+
+		total += lhs * rhs
+	}
+
+	return total
+}
+
+func part2(name string) int {
+	program := files.Read(name)
+	re := regexp.MustCompile(`(do\(\))|(don't\(\))|(mul\(\d{1,3},\d{1,3}\))`)
+	matches := re.FindAllString(program, -1)
+	total := 0
+	enabled := true
+
+	for _, m := range matches {
+		if strings.HasPrefix(m, "mul") && enabled {
+			parts := strings.Split(m, ",")
+			lhs := utils.MustIntFromString(parts[0][4:])
+			rhs := utils.MustIntFromString(parts[1][:len(parts[1])-1])
+
+			total += lhs * rhs
+		}
+
+		if strings.HasPrefix(m, "do(") {
+			enabled = true
+		}
+
+		if strings.HasPrefix(m, "don") {
+			enabled = false
+		}
+	}
+
+	return total
+}

go/2024/puzzles/day03/main_test.go

@@ -0,0 +1,35 @@
+package main
+
+import (
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+)
+
+func TestPart1(t *testing.T) {
+	t.Run("Part 1", func(t *testing.T) {
+		expected := 161
+		actual := part1("test-input.txt")
+		assert.Equal(t, expected, actual)
+	})
+}
+
+func TestPart2(t *testing.T) {
+	t.Run("Part 2", func(t *testing.T) {
+		expected := 48
+		actual := part2("test-input-part2.txt")
+		assert.Equal(t, expected, actual)
+	})
+}
+
+func BenchmarkPart1(b *testing.B) {
+	for i := 0; i < b.N; i++ {
+		part1("input.txt")
+	}
+}
+
+func BenchmarkPart2(b *testing.B) {
+	for i := 0; i < b.N; i++ {
+		part2("input.txt")
+	}
+}

go/2024/puzzles/day03/test-input-part2.txt

@@ -0,0 +1 @@
+xmul(2,4)&mul[3,7]!^don't()_mul(5,5)+mul(32,64](mul(11,8)undo()?mul(8,5))

go/2024/puzzles/day03/test-input.txt

@@ -0,0 +1 @@
+xmul(2,4)%&mul[3,7]!@^do_not_mul(5,5)+mul(32,64]then(mul(11,8)mul(8,5))