Given an array ? of numbers and a
window size ?, the sliding window ending at index ? is the subarray
?[? − ? + 1], ⋯ , ?[?] if ? ≥ ? − 1, and ?[0], ⋯ , ?[?] otherwise.
For example, if ? = [0, 2, 4, 6, 8] and ? = 3, then the sliding
windows ending at indices 0, 1, 2, 3 and 4 are respectively [0],
[0, 2], [0, 2, 4], [2, 4, 6], and...