much better day13 after looking at others

2022/go/day13/day13.go

@@ -0,0 +1,86 @@
+package day13
+
+import (
+	_ "fmt"
+	"encoding/json"
+	"sort"
+)
+
+func Part1(input []string) int {
+	sum := 0
+	for i := 0; i < len(input); i += 3 {
+		left, right := input[i], input[i+1]
+
+		if isOrderRight(left, right) {
+			sum += i/3 + 1
+		}
+	}
+	return sum
+}
+
+func Part2(input []string) int {
+	var trimmed []string
+	for _, str := range input {
+		if str != "" {
+			trimmed = append(trimmed, str)
+		}
+	}
+	trimmed = append(trimmed, "[[2]]", "[[6]]")
+	sort.Slice(trimmed, func(i, j int) bool {
+		return isOrderRight(trimmed[i], trimmed[j])
+	})
+
+	start := 0
+	end := 0
+	for i, value := range trimmed {
+		if value == "[[2]]" {
+			start = i + 1
+		}
+		if value == "[[6]]" {
+			end = i + 1
+			return start * end
+		}
+	}
+	return 0
+}
+
+func isOrderRight(left, right string) bool {
+	var l, r = unmarshal(left, right)
+
+	if cmp(l, r) <= 0 {
+		return true
+	}
+
+	return false
+}
+
+func unmarshal(left, right string) (any, any) {
+	var l, r any
+
+	json.Unmarshal([]byte(left), &l)
+	json.Unmarshal([]byte(right), &r)
+
+	return l, r
+}
+
+func cmp(left, right any) int {
+	l, lok := left.([]any)
+	r, rok := right.([]any)
+
+	switch {
+	case !lok && !rok:
+		return int(left.(float64) - right.(float64))
+	case !lok:
+		l = []any{left}
+	case !rok:
+		r = []any{right}
+	}
+
+	for i := 0; i < len(l) && i < len(r); i++ {
+		if res := cmp(l[i], r[i]); res != 0 {
+			return res
+		}
+	}
+
+	return len(l) - len(r)
+}