Completed part 1 of Day 21 puzzle, with help to cut the number of path to explore

day21/day21.go

@@ -0,0 +1,253 @@
+package day21
+
+import (
+	"fmt"
+
+	"gitea.paas.celticinfo.fr/oabrivard/aoc2023/utils"
+)
+
+type Coord struct {
+	row int
+	col int
+}
+
+func BFS1(matrix [][]byte, root Coord, maxSteps int) int {
+	height := len(matrix)
+	width := len(matrix[0])
+	queue := utils.NewQueue[*Coord]()
+
+	matrix[root.row][root.col] = 'O'
+	queue.Enqueue(&root)
+
+	moves := 0
+	for moves < maxSteps {
+		//fmt.Println(moves + 1)
+		newQueue := utils.NewQueue[*Coord]()
+
+		for queue.HasElement() {
+			coord := queue.Dequeue()
+			matrix[coord.row][coord.col] = '.'
+
+			if coord.row > 0 && matrix[coord.row-1][coord.col] != '#' {
+				newCoord := Coord{coord.row - 1, coord.col}
+				newQueue.Enqueue(&newCoord)
+				matrix[newCoord.row][newCoord.col] = 'O'
+			}
+
+			if coord.row < height-1 && matrix[coord.row+1][coord.col] != '#' {
+				newCoord := Coord{coord.row + 1, coord.col}
+				newQueue.Enqueue(&newCoord)
+				matrix[newCoord.row][newCoord.col] = 'O'
+			}
+
+			if coord.col > 0 && matrix[coord.row][coord.col-1] != '#' {
+				newCoord := Coord{coord.row, coord.col - 1}
+				newQueue.Enqueue(&newCoord)
+				matrix[newCoord.row][newCoord.col] = 'O'
+			}
+
+			if coord.col < width-1 && matrix[coord.row][coord.col+1] != '#' {
+				newCoord := Coord{coord.row, coord.col + 1}
+				newQueue.Enqueue(&newCoord)
+				matrix[newCoord.row][newCoord.col] = 'O'
+			}
+		}
+
+		queue = newQueue
+		moves++
+	}
+
+	// count 'O' in matrix
+	count := 0
+	for r := range matrix {
+		for _, b := range matrix[r] {
+			if b == 'O' {
+				count++
+			}
+		}
+	}
+
+	return count
+}
+
+func redrawFromCache(matrix [][]byte, cacheQueue utils.Queue[*Coord]) {
+	for _, coord := range cacheQueue.GetData() {
+		if coord != nil {
+			matrix[coord.row][coord.col] = 'O'
+		}
+	}
+}
+
+func BFS2(matrix [][]byte, root Coord, maxSteps int) int {
+	height := len(matrix)
+	width := len(matrix[0])
+	queue := utils.NewQueue[*Coord]()
+
+	cache := make([][]utils.Queue[*Coord], height)
+	for r, row := range matrix {
+		cache[r] = make([]utils.Queue[*Coord], width)
+		for c := range row {
+			cache[r][c] = utils.NewQueue[*Coord]()
+		}
+	}
+
+	matrix[root.row][root.col] = 'O'
+	queue.Enqueue(&root)
+
+	moves := 0
+	for moves < maxSteps {
+		fmt.Println(moves + 1)
+		newQueue := utils.NewQueue[*Coord]()
+
+		for queue.HasElement() {
+			coord := queue.Dequeue()
+
+			if cache[coord.row][coord.col].HasElement() {
+
+				matrix[coord.row][coord.col] = '.'
+				redrawFromCache(matrix, cache[coord.row][coord.col])
+
+			} else {
+				cacheQueue := utils.NewQueue[*Coord]()
+				matrix[coord.row][coord.col] = '.'
+
+				if coord.row > 0 && matrix[coord.row-1][coord.col] != '#' {
+					newCoord := Coord{coord.row - 1, coord.col}
+					newQueue.Enqueue(&newCoord)
+					matrix[newCoord.row][newCoord.col] = 'O'
+					cacheQueue.Enqueue(&newCoord)
+				}
+
+				if coord.row < height-1 && matrix[coord.row+1][coord.col] != '#' {
+					newCoord := Coord{coord.row + 1, coord.col}
+					newQueue.Enqueue(&newCoord)
+					matrix[newCoord.row][newCoord.col] = 'O'
+					cacheQueue.Enqueue(&newCoord)
+				}
+
+				if coord.col > 0 && matrix[coord.row][coord.col-1] != '#' {
+					newCoord := Coord{coord.row, coord.col - 1}
+					newQueue.Enqueue(&newCoord)
+					matrix[newCoord.row][newCoord.col] = 'O'
+					cacheQueue.Enqueue(&newCoord)
+				}
+
+				if coord.col < width-1 && matrix[coord.row][coord.col+1] != '#' {
+					newCoord := Coord{coord.row, coord.col + 1}
+					newQueue.Enqueue(&newCoord)
+					matrix[newCoord.row][newCoord.col] = 'O'
+					cacheQueue.Enqueue(&newCoord)
+				}
+
+				cache[coord.row][coord.col] = cacheQueue
+			}
+		}
+
+		queue = newQueue
+		moves++
+	}
+
+	// count 'O' in matrix
+	count := 0
+	for r := range matrix {
+		for _, b := range matrix[r] {
+			if b == 'O' {
+				count++
+			}
+		}
+	}
+
+	return count
+}
+
+func BFS3(matrix [][]byte, root Coord, maxSteps int) int {
+	height := len(matrix)
+	width := len(matrix[0])
+	queue := utils.NewQueue[*Coord]()
+
+	matrix[root.row][root.col] = 'O'
+	queue.Enqueue(&root)
+
+	moves := 0
+	for moves < maxSteps {
+		//fmt.Println(moves + 1)
+		newQueue := utils.NewQueue[*Coord]()
+		coordInQueue := map[Coord]bool{}
+
+		for queue.HasElement() {
+			coord := queue.Dequeue()
+			matrix[coord.row][coord.col] = '.'
+
+			if coord.row > 0 && matrix[coord.row-1][coord.col] != '#' {
+				newCoord := Coord{coord.row - 1, coord.col}
+				if !coordInQueue[newCoord] {
+					newQueue.Enqueue(&newCoord)
+					matrix[newCoord.row][newCoord.col] = 'O'
+					coordInQueue[newCoord] = true
+				}
+			}
+
+			if coord.row < height-1 && matrix[coord.row+1][coord.col] != '#' {
+				newCoord := Coord{coord.row + 1, coord.col}
+				if !coordInQueue[newCoord] {
+					newQueue.Enqueue(&newCoord)
+					matrix[newCoord.row][newCoord.col] = 'O'
+					coordInQueue[newCoord] = true
+				}
+			}
+
+			if coord.col > 0 && matrix[coord.row][coord.col-1] != '#' {
+				newCoord := Coord{coord.row, coord.col - 1}
+				if !coordInQueue[newCoord] {
+					newQueue.Enqueue(&newCoord)
+					matrix[newCoord.row][newCoord.col] = 'O'
+					coordInQueue[newCoord] = true
+				}
+			}
+
+			if coord.col < width-1 && matrix[coord.row][coord.col+1] != '#' {
+				newCoord := Coord{coord.row, coord.col + 1}
+				if !coordInQueue[newCoord] {
+					newQueue.Enqueue(&newCoord)
+					matrix[newCoord.row][newCoord.col] = 'O'
+					coordInQueue[newCoord] = true
+				}
+			}
+		}
+
+		queue = newQueue
+		moves++
+	}
+
+	// count 'O' in matrix
+	count := 0
+	for r := range matrix {
+		for _, b := range matrix[r] {
+			if b == 'O' {
+				count++
+			}
+		}
+	}
+
+	return count
+}
+
+func Part1(lines []string, maxSteps int) int {
+	matrix := make([][]byte, len(lines))
+
+	var root Coord
+	for r, line := range lines {
+		matrix[r] = make([]byte, len(line))
+		for c, b := range line {
+			matrix[r][c] = byte(b)
+			if b == 'S' {
+				root.row = r
+				root.col = c
+			}
+		}
+	}
+
+	result := BFS3(matrix, root, maxSteps)
+
+	return result
+}

day21/day21_test.go

@@ -0,0 +1,64 @@
+package day21
+
+import (
+	"fmt"
+	"testing"
+
+	"gitea.paas.celticinfo.fr/oabrivard/aoc2023/utils"
+)
+
+func TestPart1(t *testing.T) {
+	lines := []string{
+		"...........",
+		".....###.#.",
+		".###.##..#.",
+		"..#.#...#..",
+		"....#.#....",
+		".##..S####.",
+		".##..#...#.",
+		".......##..",
+		".##.#.####.",
+		".##..##.##.",
+		"...........",
+	}
+
+	result := Part1(lines, 1)
+
+	if result != 2 {
+		t.Fatalf("expected 2, got %d", result)
+	}
+
+	result = Part1(lines, 2)
+
+	if result != 4 {
+		t.Fatalf("expected 4, got %d", result)
+	}
+
+	result = Part1(lines, 3)
+
+	if result != 6 {
+		t.Fatalf("expected 6, got %d", result)
+	}
+
+	result = Part1(lines, 6)
+
+	if result != 16 {
+		t.Fatalf("expected 16, got %d", result)
+	}
+
+	for i := 1; i < 20; i++ {
+		result = Part1(lines, i)
+
+		fmt.Println(i, " : ", result)
+	}
+}
+
+func TestPart1WithInput(t *testing.T) {
+	lines := utils.ReadLines("input.txt")
+
+	result := Part1(lines, 64)
+
+	if result != 3758 {
+		t.Fatalf("expected 3758, got %d", result)
+	}
+}

day21/input.txt

@@ -0,0 +1,131 @@
+...................................................................................................................................
+..##....#...#.............#......................#......#..............#....#....#.#...............#......#.....#.....#............
+..##.......#......#...###..#...#............................................................#............#..#.....#................
+.....##...#.......................#..#.......#...#.#..#..................................#.........#.............#.#.##............
+............##....................#.....#........#..##....................#..........#...........#...............................#.
+..#.......#...........................#..#.##..#.....##.........#......................#...#...##.........#.............#.#....#...
+.....##.................#.#.###..#.........#................................#.......#....#..#.........#...#.......##..#..........#.
+.#....#.........#.......#....#.##..#.....#........................#.............#......#.......#...............#......#.........#..
+......#.............#......#.#................#...#..........................#...........#..#.....#.......#...........#....#...#...
+..........#....#...............#....................#.............#.............##..#.#.#.#.......#...........##..............#....
+..###.....#......#.......#...#....#.....#.........#...................................#.#....#..#..#...#...#......#................
+....#.........#.#..........##.#............#....................................#....#..............###............#....#.......#..
+....#....#............#...............#.....................#...#.#...#..................#.............................#...........
+..............#...#.........#......#.....#...............#...........................#.............#...#...........................
+.................#............#............#.#.....................#.....#..........#..#..#..##..........#.............#...#.......
+................##......#.............#..............................#....#............#..#.........##........##......#..........#.
+......#..........#...#..#............#..#.....................##...#....#.#.................................#.....#...........##...
+..........#.....#......#...#......#......##...........#.....#...........#.#..#................#..#..#.....#...#......#...#...#...#.
+..........#........#...#...........##....#.........#...#.....#...............#........................#...#.................#......
+.........#.....#...#....#.....#.......................##...#......#........................#.............#.......#....#..#....#....
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+...#........#....#.#........##....#..#.............##.....#....#.......#......#.......................#...#.............#........#.
+.......#...###..#..................#.............#......#.............................................#....#.......#......#..#.#...
+....................................##.........#..............#...........#.................##....#..............#.#........#......
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+...........#.............#........#...........#............................##....#...#........#..........##.##....#.....#.#........
+.#..................##..#.......#.............#........#..#.#........#............#...................#.#...##.#.#.................
+.....#.....#.....#...........#.#....................#.....#..#..#............#.........#.........#......#......#...............#...
+.....#........#..#....#..............................#..#...........#............#....#.#...................#.....#.#........#..#..
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+.................#.......#.........#...........#.......#.......#...#....................###......#.....#..#.....#..............#...
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+.......#..###.............#..#........#..................#........................#...................#...#..........##....#.......
+.......#................##...................#.................................#.#.....#..#............#.......#........#..........
+.................................................................S.................................................................
+........###..#.........#.........##..............#..............#.#.....#.......##.......#.....#...#.............#.................
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+.#..............#....#.......#........................#........#........#.#.#...#..........#........#..##..#...#..#...........#....
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+.#.................#..............#.................#..........#.....#..................#..................#.......................
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+......#.............#.....#...#.............#.......................##....##............#.##..#..#.......#......................#..
+...#...............#.........#.#...........#......#.....##..#...#..#.........#.#....#......#...#....#......#.#...................#.
+.......#...............#..##.......#..#.....#.....#.....#..#.#....##..#....#..........##........#.........................#...#....
+.......#..#.................##..............#.......#.#....................#.#....#....#..................#............##..........
+.......#.............#.............#....#.#.###...........#....#...#......#........#......#.....#........#...#.....................
+........#.....................#.#...#....................................#..#..#....#..#.......#.......................#.#....#....
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+......#................#....#................#............#.#...#......#...............#............#..##....#..................#..
+.........#..................................#.#...........#..................................#............#.#..........##..##.#....
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+....####...........#..#....#.............#.....#...........#...#..........................#..#....#.....#..#...........#.........#.
+.....#.#.....#...........................#.....#...........#...............................##...............##..#.#.#.........#....
+.##............#.#.#.#....##.#...#.#.............................................#.........#......#.#.............#...##...........
+.#....#.................#.#....#............#............................................#........#...........#..#.................
+..................#....#.##.#.#.#..........#........#.............#....................#...........#.....#.........................
+.........#...#.........#..................#........#...............#.................#......##........#........#.#.#.......##....#.
+.......#.......#......#.......##........#....#....#.#.......................................#..............#.....#.....#...#..#....
+......#.................#.........##....#.......................#...............#.#.....................#..#....###.#........##....
+.......#....#.....#.............................................................#..........#..#.............#..#.#..#..............
+.#.....#................#...#....#..#....##..#..##........................................#...#..............#.....#...........##..
+........#....#...##..#.....#.#.........#..............#.........................................................#......#..#.....##.
+....#..#.#....#..............................#.#.....##..##...........................#...............#......#.....................
+.##.....#.#...........##.......#........#....#.........................##.#......#.........................#.......................
+...................................................................................................................................

utils/queue.go

@@ -0,0 +1,45 @@
+package utils
+
+type Queue[T any] struct {
+	data []T
+	len  int
+}
+
+// New creates an empty stack
+func NewQueue[T any]() Queue[T] {
+	q := Queue[T]{
+		[]T{},
+		0,
+	}
+
+	return q
+}
+
+// Push pushes the value v on top of stack s.
+func (q *Queue[T]) Enqueue(v T) {
+	q.data = append(q.data, v)
+	q.len++
+}
+
+func (q *Queue[T]) Dequeue() T {
+	if !q.HasElement() {
+		panic("called Dequeue() on an empty queue")
+	}
+
+	value := q.data[0]
+	var zeroValue T
+	q.data[0] = zeroValue
+	q.data = q.data[1:]
+
+	q.len--
+
+	return value
+}
+
+func (q *Queue[T]) HasElement() bool {
+	return q.len > 0
+}
+
+func (q *Queue[T]) GetData() []T {
+	return q.data
+}

utils/utils.go

@@ -191,3 +191,12 @@ func Map[T, M any](s []T, f func(T) M) []M {
 	}
 	return res
 }
+
+func DuplicateMatrix[T any](matrix [][]T) [][]T {
+	duplicate := make([][]T, len(matrix))
+	for i := range matrix {
+		duplicate[i] = make([]T, len(matrix[i]))
+		copy(duplicate[i], matrix[i])
+	}
+	return duplicate
+}