Count the Countdown Sequences

A countdown sequence is a descending sequence of k integers from k down to 1 (e.g. 5, 4, 3, 2, 1). Write a function that returns a list [x, y] where x is the number that represents how many of countdown sequences are in a given list and y is a list of those sequences in order which they appear in the list.

Examples

final_countdown([4, 8, 3, 2, 1, 2]) ➞ [1, [[3, 2, 1]]]
# In this example we have 1 countdown sequence: 3, 2, 1

final_countdown([4, 4, 5, 4, 3, 2, 1, 8, 3, 2, 1]) ➞ [2, [[5, 4, 3, 2, 1], [3, 2, 1]]]
# We have 2 countdown sequences:
# 5, 4, 3, 2, 1 and 3, 2, 1

final_countdown([4, 3, 2, 1, 3, 2, 1, 1]) ➞ [3, [[4, 3, 2, 1], [3, 2, 1], [1]]]
# We have 3 countdown sequences:
# 4, 3, 2, 1 ; 3, 2, 1 and 1

final_countdown([1, 1, 2, 1]) ➞ [3, [[1], [1], [2, 1]]]

final_countdown([]) ➞  [0, []]

Notes

• [1] is a valid countdown sequence.
• All numbers will be greater than 0.