feat: completed day 10 for advent of code

2025/cmd/root.go

@@ -18,18 +18,20 @@ import (
 	"cpatino.com/advent-of-code/2025/day07"
 	"cpatino.com/advent-of-code/2025/day08"
 	"cpatino.com/advent-of-code/2025/day09"
+	"cpatino.com/advent-of-code/2025/day10"
 )
 
 var days = map[int]func(string) (any, any){
-	1: day01.Run,
-	2: day02.Run,
-	3: day03.Run,
-	4: day04.Run,
-	5: day05.Run,
-	6: day06.Run,
-	7: day07.Run,
-	8: day08.Run,
-	9: day09.Run,
+	1:  day01.Run,
+	2:  day02.Run,
+	3:  day03.Run,
+	4:  day04.Run,
+	5:  day05.Run,
+	6:  day06.Run,
+	7:  day07.Run,
+	8:  day08.Run,
+	9:  day09.Run,
+	10: day10.Run,
 }
 
 var rootCmd = &cobra.Command{

2025/day10/day10.go

@@ -0,0 +1,170 @@
+package day10
+
+import (
+	"bufio"
+	"math"
+	"os"
+	"strconv"
+	"strings"
+)
+
+type Combination struct {
+	incr    []int
+	presses int
+}
+
+func parse(line string) (goalBits []int, buttons [][]int, requirements []int) {
+	fields := strings.Fields(line)
+	pattern := fields[0][1 : len(fields[0])-1]
+	for i := 0; i < len(pattern); i++ {
+		if pattern[i] == '#' {
+			goalBits = append(goalBits, 1)
+		} else {
+			goalBits = append(goalBits, 0)
+		}
+	}
+	for i := 1; i < len(fields)-1; i++ {
+		inside := fields[i][1 : len(fields[i])-1]
+		if inside == "" {
+			buttons = append(buttons, []int{})
+			continue
+		}
+		parts := strings.Split(inside, ",")
+		var idxs []int
+		for _, p := range parts {
+			n, _ := strconv.Atoi(p)
+			idxs = append(idxs, n)
+		}
+		buttons = append(buttons, idxs)
+	}
+	last := fields[len(fields)-1][1 : len(fields[len(fields)-1])-1]
+	if last != "" {
+		for _, p := range strings.Split(last, ",") {
+			n, _ := strconv.Atoi(p)
+			requirements = append(requirements, n)
+		}
+	}
+	return
+}
+
+func buildCombinations(buttons [][]int, counters int) []Combination {
+	n := len(buttons)
+	res := make([]Combination, 0, 1<<uint(n))
+	for mask := 0; mask < 1<<uint(n); mask++ {
+		inc := make([]int, counters)
+		press := 0
+		for j := range n {
+			if (mask>>uint(j))&1 == 1 {
+				press++
+				for _, idx := range buttons[j] {
+					if 0 <= idx && idx < counters {
+						inc[idx]++
+					}
+				}
+			}
+		}
+		res = append(res, Combination{inc, press})
+	}
+	return res
+}
+
+func sameParity(a, b []int) bool {
+	for i := range a {
+		if (a[i]^b[i])&1 == 1 {
+			return false
+		}
+	}
+	return true
+}
+
+func notExceed(a, b []int) bool {
+	for i := range a {
+		if a[i] > b[i] {
+			return false
+		}
+	}
+	return true
+}
+
+func isZero(v []int) bool {
+	for _, x := range v {
+		if x != 0 {
+			return false
+		}
+	}
+	return true
+}
+
+func Part1(goalBits []int, buttons [][]int) int {
+	counters := len(goalBits)
+	best := math.MaxInt
+	for _, cb := range buildCombinations(buttons, counters) {
+		if sameParity(cb.incr, goalBits) && cb.presses < best {
+			best = cb.presses
+		}
+	}
+	if best == math.MaxInt {
+		return 0
+	}
+	return best
+}
+
+func minPressesCounters(state []int, combs []Combination) (int, bool) {
+	if isZero(state) {
+		return 0, true
+	}
+
+	best := math.MaxInt
+	for _, cb := range combs {
+		if !notExceed(cb.incr, state) || !sameParity(cb.incr, state) {
+			continue
+		}
+		next := make([]int, len(state))
+		for i := range state {
+			next[i] = (state[i] - cb.incr[i]) / 2
+		}
+		rec, ok := minPressesCounters(next, combs)
+		if ok {
+			total := 2*rec + cb.presses
+			if total < best {
+				best = total
+			}
+		}
+	}
+	if best < math.MaxInt {
+		return best, true
+	}
+	return 0, false
+}
+
+func Part2(requirements []int, buttons [][]int) int {
+	combs := buildCombinations(buttons, len(requirements))
+	ans, _ := minPressesCounters(requirements, combs)
+	return ans
+}
+
+func Run(filename string) (any, any) {
+	f, err := os.Open(filename)
+	if err != nil {
+		panic(err)
+	}
+	defer f.Close()
+
+	a, b := 0, 0
+	s := bufio.NewScanner(f)
+	for s.Scan() {
+		line := strings.TrimSpace(s.Text())
+		if line == "" {
+			continue
+		}
+		g, btns, req := parse(line)
+
+		a += Part1(g, btns)
+		b += Part2(req, btns)
+	}
+	if err := s.Err(); err != nil {
+		panic(err)
+	}
+
+	return a, b
+}

2025/day10/day10_test.go

@@ -0,0 +1,34 @@
+package day10
+
+import (
+	"os"
+	"testing"
+)
+
+type TestCase struct {
+	FileName string
+	Part1    any
+	Part2    any
+}
+
+func TestDay10(t *testing.T) {
+	tests := []TestCase{
+		{"test.txt", 7, 33},
+		{"input.txt", 409, 15489},
+	}
+
+	for _, test := range tests {
+		if _, err := os.Stat(test.FileName); os.IsNotExist(err) {
+			t.Fatalf("test file does not exist: %v", test.FileName)
+		}
+
+		part1, part2 := Run(test.FileName)
+		if test.Part1 != nil && part1 != test.Part1 {
+			t.Fatalf("%s: unexpected part1:\nwant:\t%v\ngot:\t%v", test.FileName, test.Part1, part1)
+		}
+
+		if test.Part2 != nil && part2 != test.Part2 {
+			t.Fatalf("%s: unexpected part2:\nwant:\t%v\ngot:\t%v", test.FileName, test.Part2, part2)
+		}
+	}
+}

2025/day10/test.txt

@@ -0,0 +1,3 @@
+[.##.] (3) (1,3) (2) (2,3) (0,2) (0,1) {3,5,4,7}
+[...#.] (0,2,3,4) (2,3) (0,4) (0,1,2) (1,2,3,4) {7,5,12,7,2}
+[.###.#] (0,1,2,3,4) (0,3,4) (0,1,2,4,5) (1,2) {10,11,11,5,10,5}