d13

d13/d13_test.go

@@ -0,0 +1,59 @@
+package d13
+
+import (
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+)
+
+func TestP1(t *testing.T) {
+	result := P1(`6,10
+0,14
+9,10
+0,3
+10,4
+4,11
+6,0
+6,12
+4,1
+0,13
+10,12
+3,4
+3,0
+8,4
+1,10
+2,14
+8,10
+9,0
+
+fold along y=7
+fold along x=5`)
+
+	assert.EqualValues(t, 17, result)
+}
+
+func TestP2(t *testing.T) {
+	result := P2(`6,10
+0,14
+9,10
+0,3
+10,4
+4,11
+6,0
+6,12
+4,1
+0,13
+10,12
+3,4
+3,0
+8,4
+1,10
+2,14
+8,10
+9,0
+
+fold along y=7
+fold along x=5`)
+
+	assert.EqualValues(t, 16, result)
+}

d13/p1.go

@@ -0,0 +1,81 @@
+package d13
+
+import (
+	"strconv"
+	"strings"
+)
+
+type point struct {
+	x int
+	y int
+}
+
+type fold struct {
+	line int
+	axis string
+}
+
+type paper map[point]bool
+
+func getPaperAndFolds(in string) (paper, []fold) {
+	paper := make(paper, 0)
+	folds := make([]fold, 0)
+
+	parts := strings.Split(strings.TrimSpace(in), "\n\n")
+
+	for _, pnt := range strings.Split(parts[0], "\n") {
+		xy := strings.Split(pnt, ",")
+		x, _ := strconv.Atoi(xy[0])
+		y, _ := strconv.Atoi(xy[1])
+
+		paper[point{x, y}] = true
+	}
+
+	for _, fld := range strings.Split(parts[1], "\n") {
+		dirAndLine := strings.Split(strings.Split(fld, " ")[2], "=")
+		line, _ := strconv.Atoi(dirAndLine[1])
+
+		folds = append(folds, fold{line, dirAndLine[0]})
+	}
+
+	return paper, folds
+}
+
+func foldUp(paper paper, y int) paper {
+	for pnt := range paper {
+		if pnt.y > y {
+			newY := y - (pnt.y - y)
+			delete(paper, pnt)
+			paper[point{pnt.x, newY}] = true
+		}
+	}
+
+	return paper
+}
+
+func foldLeft(paper paper, x int) paper {
+	for pnt := range paper {
+		if pnt.x > x {
+			newX := x - (pnt.x - x)
+			delete(paper, pnt)
+			paper[point{newX, pnt.y}] = true
+		}
+	}
+
+	return paper
+}
+
+func P1(in string) int {
+	paper, folds := getPaperAndFolds(in)
+
+	for _, fold := range folds {
+		if fold.axis == "y" {
+			paper = foldUp(paper, fold.line)
+		} else {
+			paper = foldLeft(paper, fold.line)
+		}
+		break
+	}
+
+	return len(paper)
+}

d13/p2.go

@@ -0,0 +1,52 @@
+package d13
+
+import "fmt"
+
+func P2(in string) int {
+	paper, folds := getPaperAndFolds(in)
+
+	for _, fold := range folds {
+		if fold.axis == "y" {
+			paper = foldUp(paper, fold.line)
+		} else {
+			paper = foldLeft(paper, fold.line)
+		}
+	}
+
+	xMax := 0
+	yMax := 0
+
+	for point := range paper {
+		if point.x > xMax {
+			xMax = point.x
+		}
+
+		if point.y > yMax {
+			yMax = point.y
+		}
+	}
+
+	lines := make([][]string, yMax+1)
+
+	for y := range lines {
+		lines[y] = make([]string, xMax+1)
+	}
+
+	for point := range paper {
+		lines[point.y][point.x] = "#"
+	}
+
+	for _, line := range lines {
+		for _, dot := range line {
+			if dot != "" {
+				fmt.Print("#")
+			} else {
+				fmt.Print(" ")
+
+			}
+		}
+		fmt.Println()
+	}
+
+	return len(paper)
+}

main.go

@@ -11,6 +11,7 @@ import (
 	"github.com/fotonmoton/aoc2021/d10"
 	"github.com/fotonmoton/aoc2021/d11"
 	"github.com/fotonmoton/aoc2021/d12"
+	"github.com/fotonmoton/aoc2021/d13"
 	"github.com/fotonmoton/aoc2021/d2"
 	"github.com/fotonmoton/aoc2021/d3"
 	"github.com/fotonmoton/aoc2021/d4"
@@ -55,4 +56,6 @@ func main() {
 	fmt.Printf("day 11 part 2: %v\n", d11.P2(client.Day(11)))
 	fmt.Printf("day 12: %v\n", d12.P1(client.Day(12)))
 	fmt.Printf("day 12 part 2: %v\n", d12.P2(client.Day(12)))
+	fmt.Printf("day 13: %v\n", d13.P1(client.Day(13)))
+	fmt.Printf("day 13 part 2: %v\n", d13.P2(client.Day(13)))
 }