Splitting and Merging Arrays

These three online assessment tasks each hide a pair search. Trying every pair runs out of time on the hidden tests, so each problem below comes with a short reason why one pass or one heap is enough.

A running minimum, a prefix sum and a min-heap carry the three solutions. Each one turns a quadratic search into a single sweep or a short run of heap pops.

The American Express angle

Amex leans on Java, and two of these overflow an int. Values in the statements reach 10^9, so two of them added together already pass the 32-bit range. Keep sums and heap entries as long from the first line. Write the brute force first and run it on the samples, then make the faster version agree with it before you submit.

American ExpressPremium lesson · Coding round

The 3 American Express problems are below.

1. 1A Premium questionCoding · Medium
2. 2A Premium questionCoding · Hard
3. 3A Premium questionCoding · Medium

Each with hints, the follow-up and a tested solution.

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