Revert "Array exercise"

This reverts commit b180a4b1823d5853b3e3a34544fa00d1d65a5d22.
Revert "Revert "Array exercise""

This reverts commit 712e60da045303f98a44862c8674a106ca287696.
Revert "Revert "Revert "Array exercise"""

This reverts commit 7c50e8d878d2bdc7a105f0826e0c0c979f36b61c.