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LeetCode 2352 (Medium) is a Google and Amazon favorite that tests whether you can convert rows and columns into hashable tuples. The optimal solution counts row tuples in a hashmap, then probes columns to count matches in O(n^2) time.
LeetCode 653 (Easy) asks if any two nodes in a BST sum to k. Google, Facebook, and Amazon frequently use it as a warm-up to test whether you can combine DFS traversal with the Two Sum hash-set pattern.
LeetCode 1027 (Medium) is a Google, Amazon, and Microsoft favorite that fuses DP with hashing. Each index keeps a hashmap from common difference to longest subsequence length, giving an elegant O(n^2) solution.
LeetCode 2364 (Medium) is a Google, Amazon, and Meta favorite. Count good pairs through a frequency map of nums[i]-i and subtract from total — a textbook complement-counting hashmap interview pattern.
LeetCode 1590 (Medium) shows up at Google, Amazon, and Microsoft. Find the shortest subarray whose sum mod P equals the total mod P, using a prefix-sum hashmap — a classic hash table FAANG pattern.