Coding

Find the next Even integer

Asked at

IDFC First Bank

1Give yourself 5 minutes

2Answer out loud, not in your head

3Then compare with the answer below

Stuck? Show a way to structure it+

01Confirm whether equality is allowed.
02Define parity for negative inputs if relevant.
03Check overflow at the maximum integer.
04Use remainder or bit parity safely.
05State the result and complexity.

Reference answer

Ask whether next even means the smallest even integer greater than x, or the smallest even integer greater than or equal to x. For the strict interpretation, return x plus two when x is even and x plus one when x is odd; for non-strict, return x when it is already even. In languages where modulo of negative values can be negative, parity is still determined by x modulo two being zero, but write conditions clearly rather than relying on a positive-only assumption. If x can equal the maximum representable integer, adding one or two may overflow; either use a wider type, return an error, or define wraparound only if the specification explicitly says so. Test zero, negative odd and even values, and the largest safe value. This is O(1) time and O(1) space. Do not overengineer it with loops, but do demonstrate that you noticed the API semantics hidden in the word next.

Then expect these follow-ups

How does integer overflow change an API contract?
Tests: constraint adaptation
Can you implement this without branches?
Tests: implementation extension

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