d10

d10/common.go

@@ -0,0 +1,5 @@
+package d10
+
+var pairs = map[rune]rune{'[': ']', '(': ')', '{': '}', '<': '>'}
+var score1 = map[rune]int{')': 3, ']': 57, '}': 1197, '>': 25137}
+var score2 = map[rune]int{')': 1, ']': 2, '}': 3, '>': 4}

d10/d10_test.go

@@ -0,0 +1,35 @@
+package d10
+
+import (
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+)
+
+func TestP1(t *testing.T) {
+	in := `[({(<(())[]>[[{[]{<()<>>
+[(()[<>])]({[<{<<[]>>(
+{([(<{}[<>[]}>{[]{[(<()>
+(((({<>}<{<{<>}{[]{[]{}
+[[<[([]))<([[{}[[()]]]
+[{[{({}]{}}([{[{{{}}([]
+{<[[]]>}<{[{[{[]{()[[[]
+[<(<(<(<{}))><([]([]()
+<{([([[(<>()){}]>(<<{{
+<{([{{}}[<[[[<>{}]]]>[]]`
+	assert.EqualValues(t, 26397, P1(in))
+}
+
+func TestP2(t *testing.T) {
+	in := `[({(<(())[]>[[{[]{<()<>>
+[(()[<>])]({[<{<<[]>>(
+{([(<{}[<>[]}>{[]{[(<()>
+(((({<>}<{<{<>}{[]{[]{}
+[[<[([]))<([[{}[[()]]]
+[{[{({}]{}}([{[{{{}}([]
+{<[[]]>}<{[{[{[]{()[[[]
+[<(<(<(<{}))><([]([]()
+<{([([[(<>()){}]>(<<{{
+<{([{{}}[<[[[<>{}]]]>[]]`
+	assert.EqualValues(t, 288957, P2(in))
+}

d10/p1.go

@@ -0,0 +1,30 @@
+package d10
+
+import "strings"
+
+func findScore1(line string) int {
+	stack := []rune{}
+	for _, current := range line {
+		if _, isLeft := pairs[current]; isLeft {
+			stack = append(stack, current)
+			continue
+		}
+
+		lastLeft := stack[len(stack)-1]
+		stack = stack[:len(stack)-1]
+
+		if current != pairs[lastLeft] {
+			return score1[current]
+		}
+
+	}
+	return 0
+}
+
+func P1(in string) int {
+	score := 0
+	for _, line := range strings.Split(in, "\n") {
+		score += findScore1(line)
+	}
+	return score
+}

d10/p2.go

@@ -0,0 +1,43 @@
+package d10
+
+import (
+	"sort"
+	"strings"
+)
+
+func findScore2(line string) int {
+	total := 0
+	stack := []rune{}
+	for _, current := range line {
+		if _, isLeft := pairs[current]; isLeft {
+			stack = append(stack, current)
+			continue
+		}
+
+		lastLeft := stack[len(stack)-1]
+		stack = stack[:len(stack)-1]
+
+		if current != pairs[lastLeft] {
+			return -1
+		}
+	}
+
+	for i := len(stack) - 1; i >= 0; i-- {
+		total = total*5 + score2[pairs[stack[i]]]
+	}
+
+	return total
+}
+
+func P2(in string) int {
+	scores := []int{}
+	for _, line := range strings.Split(in, "\n") {
+		if score := findScore2(line); score != -1 {
+			scores = append(scores, score)
+		}
+	}
+
+	sort.Slice(scores, func(i, j int) bool { return scores[i] < scores[j] })
+
+	return scores[len(scores)/2]
+}

main.go

@@ -8,6 +8,7 @@ import (
 
 	"github.com/fotonmoton/aoc2021/client"
 	"github.com/fotonmoton/aoc2021/d1"
+	"github.com/fotonmoton/aoc2021/d10"
 	"github.com/fotonmoton/aoc2021/d2"
 	"github.com/fotonmoton/aoc2021/d3"
 	"github.com/fotonmoton/aoc2021/d4"
@@ -46,4 +47,6 @@ func main() {
 	fmt.Printf("day 8 part 2: %v\n", d8.P2(client.Day(8)))
 	fmt.Printf("day 9: %v\n", d9.P1(client.Day(9)))
 	fmt.Printf("day 9 part 2: %v\n", d9.P2(client.Day(9)))
+	fmt.Printf("day 10: %v\n", d10.P1(client.Day(10)))
+	fmt.Printf("day 10 part 2: %v\n", d10.P2(client.Day(10)))
 }