AoC 2025 Day1

2025/01/code.go

@@ -0,0 +1,94 @@
+package main
+
+import (
+	"strconv"
+	"strings"
+
+	"github.com/jpillora/puzzler/harness/aoc"
+)
+
+func main() {
+	aoc.Harness(run)
+}
+
+// on code change, run will be executed 4 times:
+// 1. with: false (part1), and example input
+// 2. with: true (part2), and example input
+// 3. with: false (part1), and user input
+// 4. with: true (part2), and user input
+// the return value of each run is printed to stdout
+func run(part2 bool, input string) any {
+	// when you're ready to do part 2, remove this "not implemented" block
+	if part2 {
+
+		dial_val := 50
+		zcount := 0
+		for _, line := range strings.Split(input, "\n") {
+			if line == "" {
+				continue
+			}
+
+			dir, cstr := line[0], line[1:]
+			c, _ := strconv.Atoi(cstr)
+
+			full_rotations := c / 100
+			zcount += full_rotations
+
+			c -= full_rotations * 100
+
+			new_val := dial_val
+			if dir == 'R' {
+				new_val += c
+				if new_val > 99 {
+					new_val -= 100
+					zcount++
+				}
+			} else {
+				new_val -= c
+				if new_val < 0 {
+					new_val += 100
+					if dial_val != 0 {
+						zcount++
+					}
+				} else if new_val == 0 {
+					zcount++
+				}
+			}
+
+			dial_val = new_val
+		}
+
+		return zcount
+	}
+	// solve part 1 here
+
+	dial_val := 50
+	zcount := 0
+	for _, line := range strings.Split(input, "\n") {
+		//fmt.Printf("%v\n", line)
+		if line == "" {
+			continue
+		}
+
+		dir, cstr := line[0], line[1:]
+		c, _ := strconv.Atoi(cstr)
+		c = c % 100
+
+		if dir == 'R' {
+			dial_val += c
+		} else {
+			dial_val += (100 - c)
+		}
+
+		if dial_val >= 100 {
+			dial_val = dial_val % 100
+		}
+
+		if dial_val == 0 {
+			zcount++
+		}
+		//fmt.Printf("Pos: %v (%v)\n", dial_val, zcount)
+	}
+
+	return zcount
+}