Finished part 1 of day 12. Working on part 2.

day12p1/solution.go

@@ -0,0 +1,106 @@
+package day12p1
+
+import (
+	"fmt"
+	"io"
+	"strconv"
+	"strings"
+
+	"aoc/utils"
+)
+
+func Solve(r io.Reader) any {
+	lines := utils.ReadLines(r)
+
+	sum := int64(0)
+	for _, ln := range lines {
+		if utils.Verbose {
+			fmt.Printf("Starting %s\n", ln)
+		}
+
+		parts := strings.Fields(ln)
+
+		numbers := strings.Split(parts[1], ",")
+
+		groups := make([]int64, len(numbers))
+
+		var err error
+		for i, v := range numbers {
+			groups[i], err = strconv.ParseInt(v, 10, 64)
+			utils.Check(err, "Unable to convert %s to int64", v)
+		}
+
+		sum += findValid([]rune(parts[0]), groups)
+	}
+	return sum
+}
+
+func findValid(row []rune, groups []int64) int64 {
+	valids := int64(0)
+
+	for i, r := range row {
+		if r == '?' {
+			// replace with functional spring
+			trialA := make([]rune, len(row))
+			copy(trialA, row)
+			trialA[i] = '.'
+			if isValid(trialA, groups) {
+				valids += findValid(trialA, groups)
+			}
+
+			// replace with broken sprint
+			trialB := make([]rune, len(row))
+			copy(trialB, row)
+			trialB[i] = '#'
+			if isValid(trialB, groups) {
+				valids += findValid(trialB, groups)
+			}
+
+			return valids
+		}
+	}
+
+	if isValid(row, groups) {
+		valids = 1
+		if utils.Verbose {
+			fmt.Printf("\t%s\n", string(row))
+		}
+	}
+	return valids
+}
+
+func isValid(row []rune, groups []int64) bool {
+	cgroups := []int64{}
+
+	n := int64(0)
+
+	for _, r := range row {
+		switch r {
+		case '#':
+			n++
+		case '.':
+			if n > 0 {
+				cgroups = append(cgroups, n)
+				n = 0
+			}
+		case '?':
+			return true
+		}
+	}
+	if n > 0 {
+		cgroups = append(cgroups, n)
+	}
+	n = 0
+
+	if len(cgroups) != len(groups) {
+		return false
+	}
+
+	for i, g := range groups {
+		if cgroups[i] != g {
+			return false
+		}
+	}
+
+	return true
+}

day12p1/solution_test.go

@@ -0,0 +1,38 @@
+package day12p1
+
+import (
+	"strings"
+	"testing"
+
+	"aoc/utils"
+)
+
+var testInput = `???.### 1,1,3
+.??..??...?##. 1,1,3
+?#?#?#?#?#?#?#? 1,3,1,6
+????.#...#... 4,1,1
+????.######..#####. 1,6,5
+?###???????? 3,2,1`
+
+func TestSolve(t *testing.T) {
+	tests := []struct {
+		input  string
+		answer int64
+	}{
+		{testInput, 21},
+	}
+
+	if testing.Verbose() {
+		utils.Verbose = true
+	}
+
+	for _, test := range tests {
+		r := strings.NewReader(test.input)
+
+		result := Solve(r).(int64)
+
+		if result != test.answer {
+			t.Errorf("Expected %d, got %d", test.answer, result)
+		}
+	}
+}

day12p2/solution.go

@@ -0,0 +1,158 @@
+package day12p2
+
+import (
+	"fmt"
+	"io"
+	"strconv"
+	"strings"
+
+	"aoc/utils"
+)
+
+func Solve(r io.Reader) any {
+	lines := utils.ReadLines(r)
+
+	sum := int64(0)
+	for _, ln := range lines {
+		if utils.Verbose {
+			fmt.Printf("Starting %s\n", ln)
+		}
+
+		parts := strings.Fields(ln)
+
+		numbers := strings.Split(parts[1], ",")
+
+		groups := make([]int64, len(numbers)*5)
+
+		for i, v := range numbers {
+			n, err := strconv.ParseInt(v, 10, 64)
+			utils.Check(err, "Unable to convert %s to int64", v)
+			for j := 0; j < 5; j++ {
+				groups[i+len(numbers)*j] = n
+			}
+		}
+
+		var bld strings.Builder
+		for i := 0; i < 5; i++ {
+			bld.WriteString(parts[0])
+			if i < 4 {
+				bld.WriteString("?")
+			}
+		}
+
+		if utils.Verbose {
+			fmt.Printf("\texpanded: %s\n", bld.String())
+		}
+		valid := findValid([]rune(bld.String()), groups)
+		if utils.Verbose {
+			fmt.Printf("\tValid: %d\n\n", valid)
+		}
+		sum += valid
+	}
+	return sum
+}
+
+func findValid(row []rune, groups []int64) int64 {
+	valids := int64(0)
+
+	for i, r := range row {
+		if r == '?' {
+			// replace with functional spring
+			trialA := make([]rune, len(row))
+			copy(trialA, row)
+			trialA[i] = '.'
+			if isValid(trialA, groups) {
+				valids += findValid(trialA, groups)
+			}
+
+			// replace with broken sprint
+			trialB := make([]rune, len(row))
+			copy(trialB, row)
+			trialB[i] = '#'
+			if isValid(trialB, groups) {
+				valids += findValid(trialB, groups)
+			}
+
+			return valids
+		}
+	}
+
+	if isValid(row, groups) {
+		valids = 1
+		// if utils.Verbose {
+		// 	fmt.Printf("\t%s\n", string(row))
+		// }
+	}
+	return valids
+}
+
+func isValid(row []rune, groups []int64) bool {
+	cgroups := []int64{}
+
+	n := int64(0)
+	sum := int64(0)
+	empties := int64(0)
+	firstEmpty := false
+
+	// To add:
+	// find minimum possible groups
+	// by checking for '.' between remaining '#'
+	// also: if !firstEmpty sum==sum(groups)
+
+	for _, r := range row {
+		switch r {
+		case '#':
+			n++
+			sum++
+		case '.':
+			if !firstEmpty && n > 0 {
+				cgroups = append(cgroups, n)
+				n = 0
+			}
+		case '?':
+			empties++
+			if !firstEmpty && n > 0 {
+				cgroups = append(cgroups, n)
+			}
+			n = 0
+			firstEmpty = true
+		}
+	}
+	if !firstEmpty && n > 0 {
+		cgroups = append(cgroups, n)
+	}
+	n = 0
+
+	if !firstEmpty && len(cgroups) != len(groups) {
+		return false
+	}
+
+	if len(cgroups) > len(groups) {
+		// more groups already made than allowed
+		return false
+	}
+
+	totalBroken := int64(0)
+	cgl := len(cgroups)
+	for i, g := range groups {
+		if i < cgl-1 && cgroups[i] != g {
+			return false
+		} else if i == cgl-1 && cgroups[i] > g {
+			// What if there are no empties? then cgroups[i] should equal g
+			return false
+		}
+		totalBroken += g
+	}
+
+	if sum > totalBroken {
+		// too many defects
+		return false
+	}
+
+	if sum+empties < totalBroken {
+		// not enough to make total broken
+		return false
+	}
+
+	return true
+}

day12p2/solution_test.go

@@ -0,0 +1,38 @@
+package day12p2
+
+import (
+	"strings"
+	"testing"
+
+	"aoc/utils"
+)
+
+var testInput = `???.### 1,1,3
+.??..??...?##. 1,1,3
+?#?#?#?#?#?#?#? 1,3,1,6
+????.#...#... 4,1,1
+????.######..#####. 1,6,5
+?###???????? 3,2,1`
+
+func TestSolve(t *testing.T) {
+	tests := []struct {
+		input  string
+		answer int64
+	}{
+		{testInput, 525152},
+	}
+
+	if testing.Verbose() {
+		utils.Verbose = true
+	}
+
+	for _, test := range tests {
+		r := strings.NewReader(test.input)
+
+		result := Solve(r).(int64)
+
+		if result != test.answer {
+			t.Errorf("Expected %d, got %d", test.answer, result)
+		}
+	}
+}