Day01

2025/gareth/day01/day01.go

@@ -0,0 +1,64 @@
+package day01
+
+import (
+	"strconv"
+	"strings"
+)
+
+func Part1(input string) int {
+	lines := strings.Split(input, "\n")
+
+	position := 50
+	output := 0
+
+	for _, line := range lines {
+		direction := line[0]
+		amount, _ := strconv.Atoi(line[1:])
+
+		if direction == 'R' {
+			position += amount
+			for position > 99 {
+				position -= 100
+			}
+		} else if direction == 'L' {
+			position -= amount
+			for position < 0 {
+				position += 100
+			}
+		}
+
+		if position == 0 {
+			output++
+		}
+	}
+
+	return output
+}
+
+func Part2(input string) int {
+	lines := strings.Split(input, "\n")
+	position := 50
+	output := 0
+
+	for _, line := range lines {
+		direction := line[0]
+		amount, _ := strconv.Atoi(line[1:])
+
+		step := 1
+		if direction == 'L' {
+			step = -1
+		}
+
+		for i := 0; i < amount; i++ {
+			position = (position + step) % 100
+			if position < 0 {
+				position += 100
+			}
+			if position == 0 {
+				output++
+			}
+		}
+	}
+
+	return output
+}