adventofcode/2025/day10/day10.go

package main

import (
	"bufio"
	"fmt"
	"os"
	"strconv"
	"strings"

	mapset "github.com/deckarep/golang-set/v2"
)

func main() {
	f, err := os.Open("input.txt")
	if err != nil {
		panic(err)
	}
	defer f.Close()

	scanner := bufio.NewScanner(f)

	totalPresses := 0

	for scanner.Scan() {
		line := strings.TrimSpace(scanner.Text())
		if line == "" {
			continue
		}

		parts := strings.Fields(line)
		if len(parts) < 3 {
			continue
		}

		diagram := parts[0]

		pattern := diagram[1 : len(diagram)-1]
		want := 0
		for i := 0; i < len(pattern); i++ {
			if pattern[i] == '#' {
				want |= (1 << i)
			}
		}

		var have []int
		for i := 1; i < len(parts)-1; i++ {
			btn := parts[i]
			content := btn[1 : len(btn)-1]
			if len(content) == 0 {
				continue
			}
			fields := strings.Split(content, ",")
			mask := 0
			for _, f := range fields {
				idx, err := strconv.Atoi(f)
				if err != nil {
					panic(err)
				}
				mask |= (1 << idx)
			}
			have = append(have, mask)
		}

		type node struct {
			cost int
			val  int
		}

		queue := []node{{0, 0}}
		visited := mapset.NewSet[int]()
		visited.Add(0)

		foundCost := -1

		for len(queue) > 0 {
			cur := queue[0]
			queue = queue[1:]

			if cur.val == want {
				foundCost = cur.cost
				break
			}

			for _, b := range have {
				nv := cur.val ^ b
				if !visited.Contains(nv) {
					visited.Add(nv)
					queue = append(queue, node{cur.cost + 1, nv})
				}
			}
		}

		if foundCost < 0 {
			panic("no solution found for a machine")
		}

		totalPresses += foundCost
	}

	fmt.Println(totalPresses)
}