a very "good enough for AOC" kinda solution

2022/day03/main.go

@@ -0,0 +1,95 @@
+package main
+
+import (
+	_ "embed"
+	"flag"
+	"fmt"
+	"strings"
+
+	"github.com/alexchao26/advent-of-code-go/cast"
+	"github.com/alexchao26/advent-of-code-go/util"
+)
+
+//go:embed input.txt
+var input string
+
+func init() {
+	// do this in init (not main) so test file has same input
+	input = strings.TrimRight(input, "\n")
+	if len(input) == 0 {
+		panic("empty input.txt file")
+	}
+}
+
+var priorities = map[string]int{}
+
+// lol why am i using init like this...
+func init() {
+	// generate priorities
+	for i := 0; i < 26; i++ {
+		priorities[cast.ASCIIIntToChar('a'+i)] = i + 1
+		priorities[cast.ASCIIIntToChar('A'+i)] = i + 27
+	}
+}
+
+func main() {
+	var part int
+	flag.IntVar(&part, "part", 1, "part 1 or 2")
+	flag.Parse()
+	fmt.Println("Running part", part)
+
+	if part == 1 {
+		ans := part1(input)
+		util.CopyToClipboard(fmt.Sprintf("%v", ans))
+		fmt.Println("Output:", ans)
+	} else {
+		ans := part2(input)
+		util.CopyToClipboard(fmt.Sprintf("%v", ans))
+		fmt.Println("Output:", ans)
+	}
+}
+
+func part1(input string) int {
+	prioritiesSum := 0
+	for _, l := range strings.Split(input, "\n") {
+		rightHalf := l[len(l)/2:]
+		if len(rightHalf) != len(l)/2 {
+			panic("did not divide in half: " + l)
+		}
+		for i := 0; i < len(l)/2; i++ {
+			leftChar := l[i : i+1]
+			// obv unnecessary n^2 but easily fast enough...
+			if strings.Contains(rightHalf, leftChar) {
+				prioritiesSum += priorities[leftChar]
+				break
+			}
+		}
+	}
+
+	return prioritiesSum
+}
+
+func part2(input string) int {
+	prioritiesSum := 0
+	sacks := strings.Split(input, "\n")
+
+	for i := 0; i < len(sacks); i += 3 {
+		set2, set3 := stringToSet(sacks[i+1]), stringToSet(sacks[i+2])
+		for _, char := range strings.Split(sacks[i], "") {
+			if set2[char] && set3[char] {
+				prioritiesSum += priorities[char]
+				break
+			}
+		}
+	}
+
+	return prioritiesSum
+}
+
+func stringToSet(s string) map[string]bool {
+	set := map[string]bool{}
+	for _, char := range strings.Split(s, "") {
+		set[char] = true
+	}
+	return set
+}

2022/day03/main_test.go

@@ -0,0 +1,64 @@
+package main
+
+import (
+	"testing"
+)
+
+var example = `vJrwpWtwJgWrhcsFMMfFFhFp
+jqHRNqRjqzjGDLGLrsFMfFZSrLrFZsSL
+PmmdzqPrVvPwwTWBwg
+wMqvLMZHhHMvwLHjbvcjnnSBnvTQFn
+ttgJtRGJQctTZtZT
+CrZsJsPPZsGzwwsLwLmpwMDw`
+
+func Test_part1(t *testing.T) {
+	tests := []struct {
+		name  string
+		input string
+		want  int
+	}{
+		{
+			name:  "example",
+			input: example,
+			want:  157,
+		},
+		{
+			name:  "actual",
+			input: input,
+			want:  7553,
+		},
+	}
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			if got := part1(tt.input); got != tt.want {
+				t.Errorf("part1() = %v, want %v", got, tt.want)
+			}
+		})
+	}
+}
+
+func Test_part2(t *testing.T) {
+	tests := []struct {
+		name  string
+		input string
+		want  int
+	}{
+		{
+			name:  "example",
+			input: example,
+			want:  70,
+		},
+		{
+			name:  "actual",
+			input: input,
+			want:  2758,
+		},
+	}
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			if got := part2(tt.input); got != tt.want {
+				t.Errorf("part2() = %v, want %v", got, tt.want)
+			}
+		})
+	}
+}