Beginning and End Pairs

Write a function that pairs the first number in an array with the last, the second number with the second to last, etc.

Examples

pairs([1, 2, 3, 4, 5, 6, 7]) ➞ [[1, 7], [2, 6], [3, 5], [4, 4]]

pairs([1, 2, 3, 4, 5, 6]) ➞ [[1, 6], [2, 5], [3, 4]]

pairs([5, 9, 8, 1, 2]) ➞ [[5, 2], [9, 1], [8, 8]]

pairs([]) ➞ []

Notes

• If the list has an odd length, repeat the middle element twice for the last pair.
• Return an empty list if the input is an empty list.