Common Tail

Common Tail

English UK

You are given two Arrays of numbers. Elements are unique inside each Array. These Arrays may have common element(s). But we are interested in the common element(s) at the end of the Arrays. Your function should return an element, from what a common part starts and there are no different element(s) after this part - the first element of the last common part (common tail). If there is no such element (Arrays don't end with common element) your function should return null. Good luck!

Input: Two Arrays of numbers.

Output: Number or null.


assert.strictEqual(commonTail([], [1, 2, 3]), null);
assert.strictEqual(commonTail([1], [1]), 1);
assert.strictEqual(commonTail([3], [1, 2, 3]), 3);
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