Day 3: Part 1 and 2

main.go

@@ -3,7 +3,7 @@ package main
 import (
 	"fmt"
 
-	"github.com/thatguygriff/aoc2020/two"
+	"github.com/thatguygriff/aoc2020/three"
 )
 
 func main() {
@@ -12,6 +12,10 @@ func main() {
 	// fmt.Println(one.PartTwo())
 
 	// Day 2
-	fmt.Println(two.PartOne())
-	fmt.Println(two.PartTwo())
+	// fmt.Println(two.PartOne())
+	// fmt.Println(two.PartTwo())
+
+	// Day 3
+	fmt.Println(three.PartOne())
+	fmt.Println(three.PartTwo())
 }

three/day_three.go

@@ -0,0 +1,71 @@
+package three
+
+import (
+	"bufio"
+	"fmt"
+	"os"
+)
+
+type forest struct {
+	trees       [][]bool
+	rows, width int
+}
+
+func (f *forest) load(filename string) error {
+	file, err := os.Open(filename)
+	if err != nil {
+		return err
+	}
+	defer file.Close()
+
+	scanner := bufio.NewScanner(file)
+	for scanner.Scan() {
+		if f.rows == 0 {
+			f.width = len(scanner.Text())
+		}
+
+		row := make([]bool, f.width)
+		for position, possibleTree := range scanner.Text() {
+			row[position] = (string(possibleTree) == "#")
+		}
+		f.trees = append(f.trees, row)
+		f.rows++
+	}
+
+	return nil
+}
+
+func (f *forest) toboggan(right, down int) int {
+	x, y, trees := 0, 0, 0
+	for y < len(f.trees)-1 {
+		y = y + down
+		x = x + right
+		if x > (f.width - 1) {
+			x = x % f.width
+		}
+
+		if f.trees[y][x] {
+			trees++
+		}
+	}
+
+	return trees
+}
+
+func PartOne() string {
+	forest := forest{}
+	forest.load("three/trees.txt")
+	trees := forest.toboggan(3, 1)
+	return fmt.Sprintf("Found %d trees on right 3, down 1", trees)
+}
+
+func PartTwo() string {
+	forest := forest{}
+	forest.load("three/trees.txt")
+	product := forest.toboggan(1, 1) *
+		forest.toboggan(3, 1) *
+		forest.toboggan(5, 1) *
+		forest.toboggan(7, 1) *
+		forest.toboggan(1, 2)
+	return fmt.Sprintf("Found product %d of trees over 5 runs", product)
+}

three/day_three_test.go

@@ -0,0 +1,33 @@
+package three
+
+import "testing"
+
+func Test_forest_load(t *testing.T) {
+	forest := forest{}
+	if err := forest.load("sample.txt"); err != nil {
+		t.Log(err)
+		t.FailNow()
+	}
+
+	if forest.rows != 11 {
+		t.Logf("Expected 11 rows, Got %d rows", forest.rows)
+		t.FailNow()
+	}
+
+	if forest.width != 11 {
+		t.Logf("Expected 11 columns, Got %d columns", forest.rows)
+		t.FailNow()
+	}
+}
+
+func Test_forest_toboggan(t *testing.T) {
+	forest := forest{}
+	forest.load("sample.txt")
+
+	impacts := forest.toboggan(3, 1)
+
+	if impacts != 7 {
+		t.Logf("Expected 7 tree hits, actually hit %d trees", impacts)
+		t.FailNow()
+	}
+}

three/sample.txt

@@ -0,0 +1,11 @@
+..##.......
+#...#...#..
+.#....#..#.
+..#.#...#.#
+.#...##..#.
+..#.##.....
+.#.#.#....#
+.#........#
+#.##...#...
+#...##....#
+.#..#...#.#

three/trees.txt

@@ -0,0 +1,323 @@
+.........#..##..#..#........#..
+#...#..#..#...##.....##.##.#...
+....#..............#....#....#.
+#.#..#.....#...#.##..#.#.#.....
+........#..#.#..#.......#......
+.#........#.#..###.#....#.#.#..
+........#........#.......#.....
+...##..#.#.#........##.........
+#.#.##..###............#...#...
+............#....#.......###.##
+....##....##..#........#......#
+............#.#..........#.....
+#.#....#....##...#.....#.....#.
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+...........##..#.........#..#.#
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+#.#.#.#...#......#.......#...#.
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+#.#.##....#..##..##..###...###.
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+.....#.#...........#..##..##...
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