Grid and Board Problems

Grid and board tasks come up often in the Amex online assessment. Some are old LeetCode shapes, and others reward careful implementation more than any trick. Two of them are closer to geometry than to grids.

Few of them need a clever algorithm. What they need is one observation, then tidy code. Sometimes the observation is a size small enough for brute force. Sometimes it's a stopping rule for a loop that would otherwise run forever. Work it out on paper first, and the code is mostly bookkeeping.

The American Express angle

The assessment is timed, and the hidden tests go well past the samples. A simulation with no exit condition times out, and so does a pair check over a large grid. Read every constraint before you choose an approach, and write the limit next to your plan. Java is the usual language at Amex, so when an answer comes back as one long string, build it with a StringBuilder.

American ExpressPremium lesson · Coding round

The 5 American Express problems are below.

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

+ 2 more in this lesson

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

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