2022-12, path finding :)

2022/day12/main.go

@@ -0,0 +1,152 @@
+package main
+
+import (
+	_ "embed"
+	"flag"
+	"fmt"
+	"strings"
+
+	"github.com/alexchao26/advent-of-code-go/cast"
+	"github.com/alexchao26/advent-of-code-go/util"
+)
+
+//go:embed input.txt
+var input string
+
+func init() {
+	// do this in init (not main) so test file has same input
+	input = strings.TrimRight(input, "\n")
+	if len(input) == 0 {
+		panic("empty input.txt file")
+	}
+}
+
+func main() {
+	var part int
+	flag.IntVar(&part, "part", 1, "part 1 or 2")
+	flag.Parse()
+	fmt.Println("Running part", part)
+
+	if part == 1 {
+		ans := part1(input)
+		util.CopyToClipboard(fmt.Sprintf("%v", ans))
+		fmt.Println("Output:", ans)
+	} else {
+		ans := part2(input)
+		util.CopyToClipboard(fmt.Sprintf("%v", ans))
+		fmt.Println("Output:", ans)
+	}
+}
+
+var diffs = [4][2]int{
+	{0, -1},
+	{0, 1},
+	{-1, 0},
+	{1, 0},
+}
+
+func part1(input string) int {
+	grid := parseInput(input)
+
+	queue := [][3]int{}
+label:
+	for r, rows := range grid {
+		for c, cell := range rows {
+			if cell == "S" {
+				queue = append(queue, [3]int{r, c, 0})
+				break label
+			}
+		}
+	}
+	seen := map[[2]int]bool{}
+
+	for len(queue) > 0 {
+		front := queue[0]
+		queue = queue[1:]
+		if seen[[2]int{front[0], front[1]}] {
+			continue
+		}
+		seen[[2]int{front[0], front[1]}] = true
+
+		if grid[front[0]][front[1]] == "E" {
+			return front[2]
+		}
+		for _, d := range diffs {
+			nextR, nextC := front[0]+d[0], front[1]+d[1]
+			if nextR >= 0 && nextR < len(grid) && nextC >= 0 && nextC < len(grid[0]) {
+				letterDiff := distanceBetweenLetters(grid[front[0]][front[1]], grid[nextR][nextC])
+
+				if letterDiff <= 1 {
+					queue = append(queue, [3]int{nextR, nextC, front[2] + 1})
+				}
+			}
+		}
+	}
+
+	return -1
+}
+
+func part2(input string) int {
+	grid := parseInput(input)
+
+	queue := [][3]int{}
+label:
+	for r, rows := range grid {
+		for c, cell := range rows {
+			if cell == "E" {
+				queue = append(queue, [3]int{r, c, 0})
+				break label
+			}
+		}
+	}
+	seen := map[[2]int]bool{}
+
+	for len(queue) > 0 {
+		front := queue[0]
+		queue = queue[1:]
+		if seen[[2]int{front[0], front[1]}] {
+			continue
+		}
+		seen[[2]int{front[0], front[1]}] = true
+
+		if grid[front[0]][front[1]] == "a" {
+			return front[2]
+		}
+		for _, d := range diffs {
+			nextR, nextC := front[0]+d[0], front[1]+d[1]
+			if nextR >= 0 && nextR < len(grid) && nextC >= 0 && nextC < len(grid[0]) {
+				letterDiff := distanceBetweenLetters(grid[front[0]][front[1]], grid[nextR][nextC])
+
+				if letterDiff >= -1 {
+					queue = append(queue, [3]int{nextR, nextC, front[2] + 1})
+				}
+			}
+		}
+	}
+
+	return -1
+}
+
+func distanceBetweenLetters(x, y string) int {
+	if x == "S" {
+		x = "a"
+	}
+	if y == "S" {
+		y = "a"
+	}
+	if y == "E" {
+		y = "z"
+	}
+	if x == "E" {
+		x = "z"
+	}
+
+	return cast.ToASCIICode(y) - cast.ToASCIICode(x)
+}
+
+func parseInput(input string) (ans [][]string) {
+	for _, line := range strings.Split(input, "\n") {
+		ans = append(ans, strings.Split(line, ""))
+	}
+	return ans
+}

2022/day12/main_test.go

@@ -0,0 +1,63 @@
+package main
+
+import (
+	"testing"
+)
+
+var example = `Sabqponm
+abcryxxl
+accszExk
+acctuvwj
+abdefghi`
+
+func Test_part1(t *testing.T) {
+	tests := []struct {
+		name  string
+		input string
+		want  int
+	}{
+		{
+			name:  "example",
+			input: example,
+			want:  31,
+		},
+		{
+			name:  "actual",
+			input: input,
+			want:  520,
+		},
+	}
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			if got := part1(tt.input); got != tt.want {
+				t.Errorf("part1() = %v, want %v", got, tt.want)
+			}
+		})
+	}
+}
+
+func Test_part2(t *testing.T) {
+	tests := []struct {
+		name  string
+		input string
+		want  int
+	}{
+		{
+			name:  "example",
+			input: example,
+			want:  29,
+		},
+		{
+			name:  "actual",
+			input: input,
+			want:  508,
+		},
+	}
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			if got := part2(tt.input); got != tt.want {
+				t.Errorf("part2() = %v, want %v", got, tt.want)
+			}
+		})
+	}
+}