package q994

func orangesRotting(grid [][]int) int {
	w, h := len(grid[0]), len(grid)
	queue := make([][3]int, 0, w+h) // row, col, minute
	nFresh, nRot := 0, 0

	for r := range grid {
		for c := range grid[0] {
			switch grid[r][c] {
			case 1:
				nFresh++
			case 2:
				nRot++
				queue = append(queue, [3]int{r, c, 0})
			}
		}
	}

	var rot = func(r, c, minute int) {
		if r < 0 || c < 0 || r >= h || c >= w || grid[r][c] != 1 {
			return
		}
		grid[r][c] = 2
		nFresh--
		nRot++
		queue = append(queue, [3]int{r, c, minute})
	}

	minutes := 0
	for ; len(queue) > 0; queue = queue[1:] {
		cur := queue[0]
		r, c, minute := cur[0], cur[1], cur[2]
		minutes = max(minute, minutes)

		rot(r, c+1, minute+1)
		rot(r, c-1, minute+1)
		rot(r+1, c, minute+1)
		rot(r-1, c, minute+1)
	}

	if nFresh == 0 {
		return minutes
	}
	return -1
}

var _ = orangesRotting