Challenge #20: 🎁 Vertical warehouse

In Santa's workshop, the elves are storing gifts 🎁 in a vertical warehouse. The gifts are dropped one by one through a column and start stacking up.

The warehouse is a matrix with # gifts and . empty spaces. You must create a dropGiftsdrop_gifts function that receives the warehouse state and an array with the columns where the gifts are dropped.

Falling rules:

• The gift falls through the indicated column from the top.
• It is placed in the lowest empty cell (.) of that column.
• If the column is full, the gift is ignored.

dropGifts(
  [
    ['.', '.', '.'],
    ['.', '#', '.'],
    ['#', '#', '.']
  ],
  [0]
)
/*
[
  ['.', '.', '.'],
  ['#', '#', '.'],
  ['#', '#', '.']
]
*/

dropGifts(
  [
    ['.', '.', '.'],
    ['#', '#', '.'],
    ['#', '#', '#']
  ],
  [0, 2]
)
/*
[
  ['#', '.', '.'],
  ['#', '#', '#'],
  ['#', '#', '#']
]
*/

dropGifts(
  [
    ['.', '.', '.'],
    ['.', '.', '.'],
    ['.', '.', '.']
  ],
  [0, 1, 2]
)
/*
[
  ['.', '.', '.'],
  ['.', '.', '.'],
  ['#', '#', '#']
]
*/

dropGifts(
  [
    ['#', '#'],
    ['#', '#']
  ],
  [0, 0]
)
/*
[
  ['#', '#'],
  ['#', '#']
]
*/

drop_gifts(
  [
    ['.', '.', '.'],
    ['.', '#', '.'],
    ['#', '#', '.']
  ],
  [0]
)
# [
#   ['.', '.', '.'],
#   ['#', '#', '.'],
#   ['#', '#', '.']
# ]

drop_gifts(
  [
    ['.', '.', '.'],
    ['#', '#', '.'],
    ['#', '#', '#']
  ],
  [0, 2]
)
# [
#   ['#', '.', '.'],
#   ['#', '#', '#'],
#   ['#', '#', '#']
# ]

drop_gifts(
  [
    ['.', '.', '.'],
    ['.', '.', '.'],
    ['.', '.', '.']
  ],
  [0, 1, 2]
)
# [
#   ['.', '.', '.'],
#   ['.', '.', '.'],
#   ['#', '#', '#']
# ]

drop_gifts(
  [
    ['#', '#'],
    ['#', '#']
  ],
  [0, 0]
)
# [
#   ['#', '#'],
#   ['#', '#']
# ]