Advent of Code: solve 2025/01 (Go)

Author: IsaacG

advent_of_code.go/aoc.go

@@ -27,6 +27,7 @@ var puzzles = map[helpers.Puzzle]helpers.Solver{
 	helpers.Puzzle{2024, 2}:  y2024.New02(),
 	helpers.Puzzle{2024, 3}:  y2024.New03(),
 	helpers.Puzzle{2024, 17}:  y2024.New17(),
+	helpers.Puzzle{2025, 1}:  y2025.New01(),
 	helpers.Puzzle{2025, 2}:  y2025.New02(),
 }
 

advent_of_code.go/y2025/01.go

@@ -0,0 +1,49 @@
+package y2025
+
+import (
+	"strconv"
+	"strings"
+
+	"isaacgood.com/aoc/helpers"
+)
+
+// Day01 solves 2025/01.
+type Day01 struct {
+	turns [][2]int
+}
+
+// New01 returns a new solver for 2025/01.
+func New01() *Day01 {
+	return &Day01{}
+}
+
+// SetInput handles input for this solver.
+func (p *Day01) SetInput(data string) {
+	for line := range strings.SplitSeq(data, "\n") {
+		turn := helpers.Atoi(line[1:])
+		step := 1
+		if line[0] == 'L' {
+			step = -1
+		}
+		p.turns = append(p.turns, [2]int{turn, step})
+	}
+}
+
+// Solve returns the solution for one part.
+func (p *Day01) Solve(part int) string {
+	var clicks uint64
+	position := 50
+	for _, turn := range p.turns {
+		step := turn[1]
+		for i := 0; i < turn[0]; i++ {
+			position += step
+			if position%100 == 0 && part == 1 {
+				clicks++
+			}
+		}
+		if position%100 == 0 && part == 0 {
+			clicks++
+		}
+	}
+	return strconv.FormatUint(clicks, 10)
+}