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Merge pull request #22 from StevanFreeborn/stevanfreeborn/feat/day-nine-part-two

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feat: day nine part two
This commit is contained in:
Stevan Freeborn
2025-12-19 06:29:05 -06:00
committed by GitHub
parent a24eb9f9d3 7910fcf932
commit c5abf62fff
4 changed files with 155 additions and 18 deletions
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README.md
+1 -1
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@@ -34,7 +34,7 @@ go test ./cmd/01
| 06 | [Problem](https://adventofcode.com/2025/day/6) | [Solution](./cmd/06/) | Part 1 I don't think it is the best solution, but it does solve it. I kicked ass on part 2. 🥳 |
| 07 | [Problem](https://adventofcode.com/2025/day/7) | [Solution](./cmd/07/) | FIFO for life. 🤣. Fuck me...part 2 I found really difficult and the use of DFS was obvious, but doing the memoizing was not. |
| 08 | [Problem](https://adventofcode.com/2025/day/8) | [Solution](./cmd/08/) | Part 1 had me down bad. I was on the right track with my original solution, but ended up doing it in a brute force way then figuring out my mistake with the original. Fuck this guy. Part 2 was so much easier once part 1 was sorted out. |
| 09 | [Problem](https://adventofcode.com/2025/day/9) | [Solution](./cmd/09/) | Part 1 was such a nice break from the madness of day 8. |
| 09 | [Problem](https://adventofcode.com/2025/day/9) | [Solution](./cmd/09/) | Part 1 was such a nice break from the madness of day 8. Basically I need to go build some video games. |
| 10 | [Problem](https://adventofcode.com/2025/day/10) | [Solution](./cmd/10/) | |
| 11 | [Problem](https://adventofcode.com/2025/day/11) | [Solution](./cmd/11/) | |
| 12 | [Problem](https://adventofcode.com/2025/day/12) | [Solution](./cmd/12/) | |
cmd/09/main.go
+125 -16
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@@ -6,35 +6,30 @@ import (
"strings"
"github.com/StevanFreeborn/advent-of-code-2025/internal/file"
"github.com/StevanFreeborn/advent-of-code-2025/internal/position"
)
func SolvePartOne(filePath string) int {
points := []struct {
x int
y int
}{}
positions := []position.Position{}
for line := range file.ReadLines(filePath) {
parts := strings.Split(line, ",")
x, _ := strconv.Atoi(parts[0])
y, _ := strconv.Atoi(parts[1])
p := struct {
x int
y int
}{x: x, y: y}
points = append(points, p)
p := position.From(y, x)
positions = append(positions, p)
}
numberOfPoints := len(points)
numberOfPositions := len(positions)
largestArea := 0
for i := range numberOfPoints {
for j := i + 1; j < numberOfPoints; j++ {
start := points[i]
end := points[j]
for i := range numberOfPositions {
for j := i + 1; j < numberOfPositions; j++ {
start := positions[i]
end := positions[j]
width := int(math.Abs(float64(end.x-start.x)) + 1)
height := int(math.Abs(float64(end.y-start.y)) + 1)
width := int(math.Abs(float64(end.Column()-start.Column())) + 1)
height := int(math.Abs(float64(end.Row()-start.Row())) + 1)
a := width * height
@@ -46,3 +41,117 @@ func SolvePartOne(filePath string) int {
return largestArea
}
// TODO: Refactor below so more understandable
func SolvePartTwo(filePath string) int {
positions := []position.Position{}
for line := range file.ReadLines(filePath) {
parts := strings.Split(line, ",")
x, _ := strconv.Atoi(parts[0])
y, _ := strconv.Atoi(parts[1])
p := position.From(y, x)
positions = append(positions, p)
}
numberOfPositions := len(positions)
largestArea := 0
for i := range numberOfPositions {
for j := i + 1; j < numberOfPositions; j++ {
start := positions[i]
end := positions[j]
rectMinRow := int(math.Min(float64(start.Row()), float64(end.Row())))
rectMaxRow := int(math.Max(float64(start.Row()), float64(end.Row())))
rectMinCol := int(math.Min(float64(start.Column()), float64(end.Column())))
rectMaxCol := int(math.Max(float64(start.Column()), float64(end.Column())))
width := int(math.Abs(float64(rectMaxCol-rectMinCol)) + 1)
height := int(math.Abs(float64(rectMaxRow-rectMinRow)) + 1)
a := width * height
if a <= largestArea {
continue
}
centerRow := int((rectMaxRow + rectMinRow) / 2)
centerCol := int((rectMaxCol + rectMinCol) / 2)
center := position.From(centerRow, centerCol)
centerIsInside := false
for i := range numberOfPositions {
edgeStart := positions[i]
edgeEndIndex := (i + 1) % numberOfPositions
edgeEnd := positions[edgeEndIndex]
isCenterVerticallyBetweenEdge := (edgeStart.Row() <= center.Row()) && (center.Row() <= edgeEnd.Row())
edgeTotalHeight := int(math.Abs(float64(edgeEnd.Row() - edgeStart.Row())))
edgeTotalWidth := int(math.Abs(float64(edgeEnd.Column() - edgeStart.Column())))
centerPercentageOfEdgeHeight := int(float64(center.Row()-edgeStart.Row()) / float64(edgeTotalHeight))
edgeColumnAtCenterRow := edgeStart.Column() + centerPercentageOfEdgeHeight*edgeTotalWidth
isCenterHorizontallyToTheLeft := center.Row() <= edgeColumnAtCenterRow
if isCenterVerticallyBetweenEdge && isCenterHorizontallyToTheLeft {
centerIsInside = !centerIsInside
}
}
if centerIsInside == false {
continue
}
isIntersectedByEdge := false
for i := range numberOfPositions {
currPos := positions[i]
nextPosIndex := (i + 1) % numberOfPositions
nextPos := positions[nextPosIndex]
if currPos.Column() == nextPos.Column() {
col := currPos.Column()
if col > rectMinCol && col < rectMaxCol {
edgeMinRow := math.Min(float64(currPos.Row()), float64(nextPos.Row()))
edgeMaxRow := math.Max(float64(currPos.Row()), float64(nextPos.Row()))
overlapStart := int(math.Max(edgeMinRow, float64(rectMinRow)))
overlapEnd := int(math.Min(edgeMaxRow, float64(rectMaxRow)))
if overlapEnd > overlapStart {
isIntersectedByEdge = true
break
}
}
} else {
row := currPos.Row()
if row > rectMinRow && row < rectMaxRow {
edgeMinCol := math.Min(float64(currPos.Column()), float64(nextPos.Column()))
edgeMaxCol := math.Max(float64(currPos.Column()), float64(nextPos.Column()))
overlapStart := int(math.Max(edgeMinCol, float64(rectMinCol)))
overlapEnd := int(math.Min(edgeMaxCol, float64(rectMaxCol)))
if overlapEnd > overlapStart {
isIntersectedByEdge = true
break
}
}
}
}
if isIntersectedByEdge {
continue
}
largestArea = a
}
}
return largestArea
}
cmd/09/main_test.go
+20
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@@ -25,3 +25,23 @@ func TestSolvePartOneWithInput(t *testing.T) {
t.Errorf("got %d but wanted %d", result, expected)
}
}
func TestSolvePartTwoWithExampleInput(t *testing.T) {
expected := 24
result := solution.SolvePartTwo("EXAMPLE.txt")
if result != expected {
t.Errorf("got %d but wanted %d", result, expected)
}
}
func TestSolvePartTwoWithInput(t *testing.T) {
expected := 1_577_956_170
result := solution.SolvePartTwo("INPUT.txt")
if result != expected {
t.Errorf("got %d but wanted %d", result, expected)
}
}
internal/position/position.go
+9 -1
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@@ -1,7 +1,11 @@
// Package position provides types and functions to represent and manipulate positions and moves on a 2D grid.
package position
import "github.com/StevanFreeborn/advent-of-code-2025/internal/move"
import (
"fmt"
"github.com/StevanFreeborn/advent-of-code-2025/internal/move"
)
type Position interface {
Row() int
@@ -32,3 +36,7 @@ func (p position) Column() int {
func (p position) Move(move move.Move) Position {
return From(p.row+move.NumberOfRows(), p.column+move.NumberOfColumns())
}
func (p position) String() string {
return fmt.Sprintf("c: %d r: %d", p.column, p.row)
}