day 10 part 1 overkill

2023/day10/main.go

@@ -0,0 +1,149 @@
+package main
+
+import (
+	_ "embed"
+	"flag"
+	"fmt"
+	"strings"
+
+	"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)
+
+	ans := pipeMaze(input, part)
+	util.CopyToClipboard(fmt.Sprintf("%v", ans))
+	fmt.Println("Output:", ans)
+}
+
+var pipes = map[string][2][2]int{
+	"|": {
+		{-1, 0}, // up
+		{1, 0},  // down
+	},
+	"-": {
+		{0, -1}, // left
+		{0, 1},  //right
+	},
+	"L": {
+		{-1, 0}, // up
+		{0, 1},  // right
+	},
+	"J": {
+		{-1, 0}, // up
+		{0, -1}, // left
+	},
+	"7": {
+		{0, -1}, // left
+		{1, 0},  // down
+	},
+	"F": {
+		{0, 1}, // right
+		{1, 0}, // down
+	},
+}
+
+func pipeMaze(input string, part int) int {
+	grid := parseInput(input)
+
+	var r, c int
+	for i, row := range grid {
+		for j, val := range row {
+			if val == "S" {
+				r = i
+				c = j
+			}
+		}
+	}
+
+	// need to find which directions are connected to the initial cell
+	// could traverse along the four directions and see which two lead back to
+	// the start... all pipes only connect two coordinates so it's actually
+	// fairly easy to traverse without creating a huge search space
+
+	// note this soultion was overkill for part 1
+	// inputs are nice and exactly two adjacent cells that connect to S
+	var loopCoords map[[2]int]bool
+	for pipeType := range pipes {
+		// assign the start square to a random pipeType, then see if it will loop
+		grid[r][c] = pipeType
+
+		seen := map[[2]int]bool{}
+		toAnalyze := [][2]int{
+			{r, c},
+		}
+		didLoop := false
+		for len(toAnalyze) > 0 {
+			coords := toAnalyze[0]
+			if seen[coords] {
+				didLoop = true
+				break
+			}
+			seen[coords] = true
+			toAnalyze = toAnalyze[1:]
+
+			if diffs, ok := pipes[grid[coords[0]][coords[1]]]; ok {
+				for _, diff := range diffs {
+					nextRow, nextCol := coords[0]+diff[0], coords[1]+diff[1]
+					if isInRange(grid, nextRow, nextCol) && !seen[[2]int{nextRow, nextCol}] {
+						toAnalyze = append(toAnalyze, [2]int{nextRow, nextCol})
+					}
+				}
+			}
+
+		}
+		if didLoop {
+			loopCoords = seen
+			break
+		}
+	}
+
+	if part == 1 {
+		return len(loopCoords) / 2
+	}
+
+	// part 2
+
+	newGrid := make([][]string, len(grid))
+	for i := 0; i < len(grid); i++ {
+		for j := 0; j < len(grid[0]); j++ {
+			if loopCoords[[2]int{i, j}] {
+				newGrid[i] = append(newGrid[i], grid[i][j])
+			} else {
+				newGrid[i] = append(newGrid[i], ".")
+			}
+		}
+	}
+
+	for _, r := range newGrid {
+		fmt.Println(r)
+	}
+
+	return -1
+}
+
+func isInRange(grid [][]string, row, col int) bool {
+	return row >= 0 && row < len(grid) && col >= 0 && col <= len(grid)
+}
+
+func parseInput(input string) (ans [][]string) {
+	for _, line := range strings.Split(input, "\n") {
+		ans = append(ans, strings.Split(line, ""))
+	}
+	return ans
+}

2023/day10/main_test.go

@@ -0,0 +1,123 @@
+package main
+
+import (
+	"testing"
+)
+
+var example = `.....
+.S-7.
+.|.|.
+.L-J.
+.....`
+
+var complexExample = `..F7.
+.FJ|.
+SJ.L7
+|F--J
+LJ...`
+
+var examplePart2 = `...........
+.S-------7.
+.|F-----7|.
+.||.....||.
+.||.....||.
+.|L-7.F-J|.
+.|..|.|..|.
+.L--J.L--J.
+...........`
+var examplePart2_2 = `..........
+.S------7.
+.|F----7|.
+.||OOOO||.
+.||OOOO||.
+.|L-7F-J|.
+.|II||II|.
+.L--JL--J.
+..........`
+var examplePart2_large = `.F----7F7F7F7F-7....
+.|F--7||||||||FJ....
+.||.FJ||||||||L7....
+FJL7L7LJLJ||LJ.L-7..
+L--J.L7...LJS7F-7L7.
+....F-J..F7FJ|L7L7L7
+....L7.F7||L7|.L7L7|
+.....|FJLJ|FJ|F7|.LJ
+....FJL-7.||.||||...
+....L---J.LJ.LJLJ...`
+var examplePart2_larger = `FF7FSF7F7F7F7F7F---7
+L|LJ||||||||||||F--J
+FL-7LJLJ||||||LJL-77
+F--JF--7||LJLJ7F7FJ-
+L---JF-JLJ.||-FJLJJ7
+|F|F-JF---7F7-L7L|7|
+|FFJF7L7F-JF7|JL---7
+7-L-JL7||F7|L7F-7F7|
+L.L7LFJ|||||FJL7||LJ
+L7JLJL-JLJLJL--JLJ.L`
+
+func Test_pipeMaze(t *testing.T) {
+	tests := []struct {
+		name  string
+		input string
+		part  int
+		want  int
+	}{
+		{
+			name:  "example",
+			input: example,
+			part:  1,
+			want:  4,
+		},
+		{
+			name:  "complexExample",
+			input: complexExample,
+			part:  1,
+			want:  8,
+		},
+		{
+			name:  "actual part 1",
+			input: input,
+			part:  1,
+			want:  6773,
+		},
+
+		// part 2
+		{
+			name:  "examplePart2",
+			input: examplePart2,
+			part:  2,
+			want:  4,
+		},
+		{
+			name:  "examplePart2_2",
+			input: examplePart2_2,
+			part:  2,
+			want:  4,
+		},
+		{
+			name:  "examplePart2_large",
+			input: examplePart2_large,
+			part:  2,
+			want:  8,
+		},
+		{
+			name:  "examplePart2_larger",
+			input: examplePart2_larger,
+			part:  2,
+			want:  10,
+		},
+		// {
+		// 	name:  "actual part 2",
+		// 	input: input,
+		// part: 2,
+		// 	want:  0,
+		// },
+	}
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			if got := pipeMaze(tt.input, tt.part); got != tt.want {
+				t.Errorf("pipeMaze() = %v, want %v", got, tt.want)
+			}
+		})
+	}
+}