feat: solve part one using a prebuild list to reduce comparisons

internal/2025/DayThree/code.go

@@ -0,0 +1,48 @@
+package daythree
+
+import (
+	"os"
+	"strings"
+
+	"advent-of-code/internal/registry"
+)
+
+func init() {
+	registry.Register("2025D3", ParseInput, PartOne, PartTwo)
+}
+
+func ParseInput(filepath string) [][]int {
+	content, _ := os.ReadFile(filepath)
+	lines := strings.Split(string(content), "\n")
+	var data [][]int
+	for _, line := range lines {
+		var bank []int
+		for _, char := range line {
+			bank = append(bank, int(char-'0'))
+		}
+		data = append(data, bank)
+	}
+	return data
+}
+
+func PartOne(data [][]int) int {
+	total := 0
+	for _, bank := range data {
+		maxAfter := make([]int, len(bank))
+		for idx := len(bank) - 2; idx >= 0; idx-- {
+			maxAfter[idx] = max(maxAfter[idx+1], bank[idx+1])
+		}
+
+		maxJoltage := 0
+		for idx := 0; idx < len(bank)-1; idx++ {
+			joltage := bank[idx]*10 + maxAfter[idx]
+			maxJoltage = max(maxJoltage, joltage)
+		}
+		total += maxJoltage
+	}
+	return total
+}
+
+func PartTwo(data [][]int) int {
+	return 0
+}