feat: solve day 2 part 2

This commit is contained in:
Stevan Freeborn
2025-12-04 06:33:21 -06:00
parent 267bbd2d81
commit 8c17524cc6
5 changed files with 145 additions and 20 deletions
+7 -3
View File
@@ -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/) | |
+18 -1
View File
@@ -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
}
}
+20
View File
@@ -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)
}
}
+43 -2
View File
@@ -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
}
}
}
}
+45 -2
View File
@@ -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)
}
}
}