Merge pull request #5 from StevanFreeborn/stevanfreeborn/feat/solve-day-two-part-two

feat: solve day 2 part 2

README.md

@@ -16,14 +16,18 @@ Each day's solution is contained in a separate package.
 
 ### Running the Solutions
 
-![TODO]: Update with instructions
+To run a specific day's solution you can run the packages tests:
+
+```pwsh
+go test ./cmd/01
+```
 
 ## Challenges
 
 | Day | Problem                                         | Solution              | Notes                                                                                                                                                                                  |
-|-----|-------------------------------------------------|-----------------------|-------------------------------------------------------------------------------------------------------------------------------------------------------------------|
+|-----|-------------------------------------------------|-----------------------|----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
 | 01  | [Problem](https://adventofcode.com/2025/day/1)  | [Solution](./cmd/01/) | Part 1 seemed straight forward enough. Part 2 completely stumped me. The trickiest part was not counting zero's twice when you ended and then started from there.                      |
-| 02  | [Problem](https://adventofcode.com/2025/day/2)  | [Solution](./cmd/02/) | Part 1 should have been super straight-forward, but some whitespace screwed up my parsing of the final range.                                                     |
+| 02  | [Problem](https://adventofcode.com/2025/day/2)  | [Solution](./cmd/02/) | Part 1 should have been super straight-forward, but some whitespace screwed up my parsing of the final range. I some how was able to stumble over a solution to part 2 rather blindly. |
 | 03  | [Problem](https://adventofcode.com/2025/day/3)  | [Solution](./cmd/03/) |                                                                                                                                                                                        |
 | 04  | [Problem](https://adventofcode.com/2025/day/4)  | [Solution](./cmd/04/) |                                                                                                                                                                                        |
 | 05  | [Problem](https://adventofcode.com/2025/day/5)  | [Solution](./cmd/05/) |                                                                                                                                                                                        |

cmd/02/main.go

@@ -18,7 +18,24 @@ func SolvePartOne(filePath string) int64 {
 	for r := range strRanges {
 		rng := rnge.From(r)
 
-		for id := range rng.InvalidIds() {
+		for id := range rng.InvalidIdsWithEqualHalves() {
+			total += id
+		}
+	}
+
+	return total
+}
+
+func SolvePartTwo(filePath string) int64 {
+	input := file.ReadAllText(filePath)
+	strRanges := strings.SplitSeq(input, SeparatorCharacter)
+
+	total := int64(0)
+
+	for r := range strRanges {
+		rng := rnge.From(r)
+
+		for id := range rng.InvalidIdsWithTwoOrMoreSeq() {
 			total += id
 		}
 	}

cmd/02/main_test.go

@@ -25,3 +25,23 @@ func TestSolvePartOneWithInput(t *testing.T) {
 		t.Errorf("expected %d, got %d", expected, result)
 	}
 }
+
+func TestSolvePartTwoWithExampleInput(t *testing.T) {
+	expected := int64(4_174_379_265)
+
+	result := solution.SolvePartTwo("EXAMPLE.txt")
+
+	if result != expected {
+		t.Errorf("expected %d, got %d", expected, result)
+	}
+}
+
+func TestSolvePartTwoWithInput(t *testing.T) {
+	expected := int64(28858486244)
+
+	result := solution.SolvePartTwo("INPUT.txt")
+
+	if result != expected {
+		t.Errorf("expected %d, got %d", expected, result)
+	}
+}

cmd/02/rnge/rnge.go

@@ -10,7 +10,8 @@ import (
 const RangeSeparatorCharacter = "-"
 
 type Range interface {
-	InvalidIds() iter.Seq[int64]
+	InvalidIdsWithEqualHalves() iter.Seq[int64]
+	InvalidIdsWithTwoOrMoreSeq() iter.Seq[int64]
 	Start() int64
 	End() int64
 }
@@ -39,7 +40,7 @@ func (r rnge) End() int64 {
 	return r.end
 }
 
-func (r rnge) InvalidIds() iter.Seq[int64] {
+func (r rnge) InvalidIdsWithEqualHalves() iter.Seq[int64] {
 	return func(yield func(int64) bool) {
 		for id := r.start; id <= r.end; id++ {
 			idStr := strconv.FormatInt(id, 10)
@@ -65,3 +66,43 @@ func (r rnge) InvalidIds() iter.Seq[int64] {
 		}
 	}
 }
+
+func (r rnge) InvalidIdsWithTwoOrMoreSeq() iter.Seq[int64] {
+	return func(yield func(int64) bool) {
+		for id := r.start; id <= r.end; id++ {
+			idStr := strconv.FormatInt(id, 10)
+			idLength := len(idStr)
+
+			isValid := true
+
+			for pLen := 1; pLen <= idLength/2; pLen++ {
+				v := idLength % pLen
+				repeatedPatterDoesNotFit := v != 0
+
+				if repeatedPatterDoesNotFit {
+					continue
+				}
+
+				pattern := idStr[:pLen]
+				numOfRepeats := idLength / pLen
+				repeatedPattern := strings.Repeat(pattern, numOfRepeats)
+
+				if repeatedPattern != idStr {
+					continue
+				}
+
+				isValid = false
+			}
+
+			if isValid {
+				continue
+			}
+
+			ok := yield(id)
+
+			if !ok {
+				return
+			}
+		}
+	}
+}

cmd/02/rnge/rnge_test.go

@@ -42,12 +42,12 @@ func TestEnd(t *testing.T) {
 	}
 }
 
-func TestInvalidIds(t *testing.T) {
+func TestInvalidIdsWithEqualValues(t *testing.T) {
 	r := rnge.From("1000-1100")
 	expectedInvalidIds := []int64{1010}
 	resultInvalidIds := []int64{}
 
-	for id := range r.InvalidIds() {
+	for id := range r.InvalidIdsWithEqualHalves() {
 		resultInvalidIds = append(resultInvalidIds, id)
 	}
 
@@ -55,3 +55,46 @@ func TestInvalidIds(t *testing.T) {
 		t.Errorf("expected invalid IDs %v, got %v", expectedInvalidIds, resultInvalidIds)
 	}
 }
+
+type TestCase struct {
+	rnge               rnge.Range
+	expectedInvalidIds []int64
+}
+
+func TestInvalidIdsWithTwoOrMoreSeq(t *testing.T) {
+	testCases := []TestCase{
+		{
+			rnge:               rnge.From("11-22"),
+			expectedInvalidIds: []int64{11, 22},
+		},
+		{
+			rnge:               rnge.From("95-115"),
+			expectedInvalidIds: []int64{99, 111},
+		},
+		{
+			rnge:               rnge.From("998-1012"),
+			expectedInvalidIds: []int64{999, 1010},
+		},
+		{
+			rnge:               rnge.From("1188511880-1188511890"),
+			expectedInvalidIds: []int64{1188511885},
+		},
+		{
+			rnge:               rnge.From("222220-222224"),
+			expectedInvalidIds: []int64{222222},
+		},
+	}
+
+	for _, c := range testCases {
+		resultInvalidIds := []int64{}
+
+		for id := range c.rnge.InvalidIdsWithTwoOrMoreSeq() {
+			resultInvalidIds = append(resultInvalidIds, id)
+		}
+
+		if slices.Equal(resultInvalidIds, c.expectedInvalidIds) == false {
+			t.Errorf("expected invalid IDs %v, got %v", c.expectedInvalidIds, resultInvalidIds)
+		}
+	}
+
+}