Common Interview Problem Patterns Questions
Familiarize yourself with typical problem patterns: string manipulation (finding substrings, counting characters), array operations (finding duplicates, sorting, searching), two-pointer techniques, basic recursion, and simple dynamic programming. Focus on problems that are LeetCode Easy to Easy-Medium difficulty.
MediumTechnical
57 practiced
Classic sliding-window: given a string s, implement longest_unique_substring_length(s) in Python that returns the length of the longest substring without repeating characters. Target O(n) time and O(min(n, alphabet)) space. Example: s = 'abcabcbb' -> return 3.
MediumTechnical
66 practiced
Implement find_anagram_indices(s, p) in Python: given a text s and pattern p, return a list of starting indices of substrings in s which are anagrams of p. Example: s = 'cbaebabacd', p = 'abc' -> return [0,6]. Aim for O(n) time.
HardTechnical
64 practiced
Zero-sum subarray: given nums (may contain positives and negatives), find length of longest subarray with sum equal to 0. Implement longest_zero_sum_subarray(nums) in Python using prefix sums and discuss complexity and how you'd handle floating point tolerance.
HardTechnical
69 practiced
Implement Longest Increasing Subsequence (LIS) function lis_length(nums) in Python that returns the length of LIS in O(n log n) time using patience sorting / tails array and binary search. Explain the tails technique and provide complexity analysis.
HardTechnical
66 practiced
Scenario-based: you need to estimate the number of distinct user IDs in a massive clickstream (>10B events) with limited memory. Describe a probabilistic algorithm or sketch you would use (e.g., Flajolet-Martin, HyperLogLog). Explain error trade-offs, memory usage, and how you'd merge summaries across partitions.
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