chore: add day13

day13/example.txt

@@ -0,0 +1,15 @@
+#.##..##.
+..#.##.#.
+##......#
+##......#
+..#.##.#.
+..##..##.
+#.#.##.#.
+
+#...##..#
+#....#..#
+..##..###
+#####.##.
+#####.##.
+..##..###
+#....#..#

day13/example00.txt

@@ -0,0 +1,7 @@
+#.##..##.
+..#.##.#.
+##......#
+##......#
+..#.##.#.
+..##..##.
+#.#.##.#.

day13/input07.txt

@@ -0,0 +1,11 @@
+##.#.##.#
+...#..#..
+.##...#..
+.##...#..
+.#.#..#..
+##.#.##.#
+.#...####
+..#.#..##
+...#...##
+.#....#.#
+.#....#.#

day13/main.go

@@ -0,0 +1,179 @@
+package main
+
+import (
+	"bufio"
+	_ "embed"
+	"fmt"
+	"strings"
+
+	aoc "go.sour.is/advent-of-code-2023"
+)
+
+var log = aoc.Log
+
+func main() { aoc.MustResult(aoc.Runner(run)) }
+
+type result struct {
+	valuePT1 int
+	valuePT2 int
+}
+
+func (r result) String() string { return fmt.Sprintf("%#v", r) }
+
+func run(scan *bufio.Scanner) (*result, error) {
+	maps := []Map{}
+	m := Map{}
+	r := &result{}
+
+	for scan.Scan() {
+		text := scan.Text()
+
+		if text == "" {
+			maps = append(maps, m)
+			m = Map{}
+		} else {
+			m = append(m, []rune(text))
+		}
+	}
+	maps = append(maps, m)
+
+	for _, m := range maps {
+		sum, sum2 := findSmudge(m)
+
+		if sum == -1 || sum2 == -1 {
+			mr := Map(aoc.Transpose(m))
+			Hsum, Hsum2 := findSmudge(mr)
+
+			if sum2 == -1 {
+				sum2 = Hsum2 * 100
+			}
+
+			if sum == -1 {
+				sum = Hsum * 100
+			}
+		}
+
+		r.valuePT1 += sum
+		r.valuePT2 += sum2
+	}
+
+	return r, nil
+}
+
+type Map [][]rune
+
+func (m Map) String() string {
+	var buf strings.Builder
+	for i, row := range m {
+		if i == 0 {
+			fmt.Fprint(&buf, "   ")
+			for j := range row {
+				fmt.Fprintf(&buf, "%d", j)
+			}
+			fmt.Fprint(&buf, "\n")
+		}
+
+		fmt.Fprintf(&buf, "%d ", i)
+		buf.WriteRune(' ')
+		buf.WriteString(string(row))
+		buf.WriteRune('\n')
+	}
+	buf.WriteRune('\n')
+	return buf.String()
+
+}
+
+// func findReflection(m Map) (int, bool) {
+// 	candidates := make(map[int]bool)
+// 	var candidateList []int
+
+// 	for _, row := range m {
+// 		for col := 1; col < len(row); col++ {
+// 			if v, ok := candidates[col]; !ok || v {
+// 				candidates[col], _ = reflects(row[:col], row[col:])
+// 			}
+// 		}
+// 		candidateList = all(candidates)
+// 		if len(candidateList) == 0 {
+// 			return 0, false
+// 		}
+// 	}
+
+// 	if len(candidateList) == 1 {
+// 		return candidateList[0], true
+// 	}
+
+// 	return 0, false
+// }
+
+type level struct {
+	blips  int
+	nequal int
+	fail   bool
+}
+
+func findSmudge(m Map) (int, int) {
+	candidates := make(map[int]level)
+
+	for _, row := range m {
+		for col := 1; col < len(row); col++ {
+			candidate := candidates[col]
+			if candidate.fail {
+				continue
+			}
+
+			eq, bl := reflects(row[:col], row[col:])
+			if !eq {
+				candidate.nequal++
+			}
+			candidate.blips += bl
+
+			if candidate.nequal > 1 || candidate.blips > 1 {
+				candidate.fail = true
+			}
+
+			candidates[col] = candidate
+		}
+	}
+
+	a, b := -1, -1
+	for i, cand := range candidates {
+		if !cand.fail && cand.blips == 1 {
+			b = i
+		}
+		if !cand.fail && cand.blips == 0 {
+			a = i
+		}
+	}
+
+	return a, b
+}
+
+func reflects(a, b []rune) (bool, int) {
+	c := min(len(a), len(b))
+
+	a = append([]rune{}, a...)
+	b = append([]rune{}, b...)
+	aoc.Reverse(a)
+	a = a[:c]
+	b = b[:c]
+
+	blips := 0
+	for i := range a {
+		if a[i] != b[i] {
+			blips++
+		}
+	}
+
+	return blips == 0, blips
+}
+
+func all[T comparable](m map[T]bool) []T {
+	lis := make([]T, 0, len(m))
+	for k, v := range m {
+		if v {
+			lis = append(lis, k)
+		}
+	}
+	return lis
+}

day13/main_test.go

@@ -0,0 +1,42 @@
+package main
+
+import (
+	"bufio"
+	"bytes"
+	"testing"
+
+	_ "embed"
+
+	"github.com/matryer/is"
+)
+
+//go:embed example.txt
+var example []byte
+
+//go:embed input.txt
+var input []byte
+
+func TestExample(t *testing.T) {
+	is := is.New(t)
+	scan := bufio.NewScanner(bytes.NewReader(example))
+
+	result, err := run(scan)
+	is.NoErr(err)
+
+	t.Log(result)
+	is.Equal(result.valuePT1, 405)
+	is.Equal(result.valuePT2, 400)
+}
+
+func TestSolution(t *testing.T) {
+	is := is.New(t)
+	scan := bufio.NewScanner(bytes.NewReader(input))
+
+	result, err := run(scan)
+	is.NoErr(err)
+
+	t.Log(result)
+	is.True(result.valuePT1 > 1704) // attempt 1
+	is.Equal(result.valuePT1, 30705)
+	is.Equal(result.valuePT2, 44615)
+}