John Deere interview questions

Round 1 – Online Assessment Question: "Given an array of non-negative integers, arrange them to form the largest possible number." Difficulty: Medium Approach: I first thought of sorting numbers in descending order but quickly realized 30 vs 3 would break this approach (330 < 303). Switched to a custom comparator: compare a+b and b+a as strings. Used functools.cmp_to_key in Python to implement the comparator. Handled edge case where the result could have leading zeros. My solution passed all hidden test cases. Round 2 – Technical Interview Discussion: The interviewer asked me to explain my approach before coding. We talked about why normal sorting fails. He asked me about time complexity — I explained: Sorting takes O(n log n) comparisons. Each comparison takes O(k) time where k is max number of digits (since we compare concatenated strings). So overall: O(n log n * k). Then he asked for edge cases: Array with single element. Array with all zeros. Array with numbers having same prefix (like [121, 12]). I wrote a dry run for [3, 30, 34, 5, 9] step by step, explaining comparisons.