Minutes until every item on a shelf spoils

from collections import deque


STEPS = ((1, 0), (-1, 0), (0, 1), (0, -1))


def minutes_to_spoil(shelf: list[list[int]]) -> int:
    rows, cols = len(shelf), len(shelf[0]) if shelf else 0
    grid = [row[:] for row in shelf]
    queue = deque((r, c) for r, row in enumerate(grid)
                  for c, item in enumerate(row) if item == 2)
    fresh = sum(row.count(1) for row in grid)
    minutes = 0
    while queue and fresh:
        minutes += 1
        for _ in range(len(queue)):
            r, c = queue.popleft()
            for dr, dc in STEPS:
                y, x = r + dr, c + dc
                if 0 <= y < rows and 0 <= x < cols and grid[y][x] == 1:
                    grid[y][x] = 2
                    fresh -= 1
                    queue.append((y, x))
    return minutes if fresh == 0 else -1

val STEPS = listOf(1 to 0, -1 to 0, 0 to 1, 0 to -1)

fun minutesToSpoil(shelf: List<List<Int>>): Int {
    val grid = shelf.map { it.toMutableList() }
    val queue = ArrayDeque<Pair<Int, Int>>()
    var fresh = 0
    for ((r, row) in grid.withIndex()) {
        for ((c, item) in row.withIndex()) {
            if (item == 2) queue.addLast(r to c)
            if (item == 1) fresh++
        }
    }
    var minutes = 0
    while (queue.isNotEmpty() && fresh > 0) {
        minutes++
        repeat(queue.size) {
            val (r, c) = queue.removeFirst()
            for ((dr, dc) in STEPS) {
                val y = r + dr
                val x = c + dc
                if (grid.getOrNull(y)?.getOrNull(x) != 1) continue
                grid[y][x] = 2
                fresh--
                queue.addLast(y to x)
            }
        }
    }
    return if (fresh == 0) minutes else -1
}