go: add «1368. Minimum Cost to Make at Least One Valid Path in a Grid»

URL:	https://leetcode.com/problems/minimum-cost-to-make-at-least-one-valid-path-in-a-grid/
Signed-off-by: Matej Focko <me@mfocko.xyz>

go/minimum-cost-to-make-at-least-one-valid-path-in-a-grid.go

@@ -0,0 +1,75 @@
+package main
+
+import aq "github.com/emirpasic/gods/v2/queues/arrayqueue"
+
+type Coord struct {
+	y int
+	x int
+}
+
+func (c *Coord) Add(rhs Coord) Coord {
+	return Coord{
+		y: c.y + rhs.y,
+		x: c.x + rhs.x,
+	}
+}
+
+func minCost(grid [][]int) int {
+	UNVISITED := 10000001
+	DIRS := []Coord{
+		Coord{0, 1},
+		Coord{0, -1},
+		Coord{1, 0},
+		Coord{-1, 0},
+	}
+
+	width, height := len(grid[0]), len(grid)
+	inBounds := func(pos Coord) bool {
+		return pos.y >= 0 && pos.y < height && pos.x >= 0 && pos.x < width
+	}
+
+	dp := make([][]int, height)
+	for i, _ := range dp {
+		dp[i] = make([]int, width)
+		for j, _ := range dp[i] {
+			dp[i][j] = UNVISITED
+		}
+	}
+	isVisited := func(pos Coord) bool {
+		return dp[pos.y][pos.x] != UNVISITED
+	}
+
+	q := aq.New[Coord]()
+
+	var dfs func(int, Coord)
+	dfs = func(cost int, pos Coord) {
+		if !inBounds(pos) || isVisited(pos) {
+			return
+		}
+
+		dp[pos.y][pos.x] = cost
+		q.Enqueue(pos)
+
+		// follow the direction
+		dirIdx := grid[pos.y][pos.x] - 1
+		dfs(cost, pos.Add(DIRS[dirIdx]))
+	}
+
+	cost := 0
+	dfs(cost, Coord{0, 0})
+
+	for !q.Empty() {
+		cost++
+
+		size := q.Size()
+		for i := 0; i < size; i++ {
+			pos, _ := q.Dequeue()
+
+			for _, dir := range DIRS {
+				dfs(cost, pos.Add(dir))
+			}
+		}
+	}
+
+	return dp[height-1][width-1]
+}