What's New?
October 2026
Arrays & Hashing · Coding Question
Check whether an array contains every integer in a given inclusive range.
Search Algorithms · Coding Question
Find the last occurrence of a character in a string, including when the character is absent.
Arrays & Hashing · Coding Question
Find the least frequent character in a string, handling ties consistently.
Linked Lists · Coding Question
Count the nodes in a circular linked list without looping indefinitely.
SQL · Coding Question
Write an anti-join that returns users who booked a flight in March 2024 but no hotel in the same window.
Linked Lists · Coding Question
Find the node where two singly linked lists merge, walking both in a single pass with no extra memory (LeetCode #160).
Trees · Coding Question
Connect each node of a perfect binary tree to its right neighbour on the same level, using the links you have already built (LeetCode #116).
Sliding Window · Coding Question
Count the most frequent substring whose length and distinct-letter count stay within given limits (LeetCode #1297).
SQL · Coding Question
From a status log, work out each industrial asset's total minutes in the DOWN state using a window function.
Arrays & Hashing · Coding Question
Capitalise the first character of each word in a string, leaving everything else untouched.
Graphs · Coding Question
Find the highest-value path that starts and ends at node 0 within a time limit, counting each visited node once (LeetCode #2065).
Trees · Coding Question
Rebuild trace trees from a flat list of spans and their parent ids, and return each span with its depth.
Graphs · Coding Question
Group employees who share an interest, directly or through a chain of colleagues, and return every group.
Tries · Coding Question
Remove every string that is a prefix of another string in the list, keeping the rest in their original order.
Arrays & Hashing · Coding Question
Pick three items in index order with strictly increasing prices so that their combined profit is as large as possible.
Graphs · Coding Question
Cluster images that are linked, directly or through other images, by similarity scores at or above a threshold.
Heaps · Coding Question
Total each customer's purchases and return the k customers with the least revenue, lowest first.
Graphs · Coding Question
Given child-parent edges describing a forest, return the root of the tree with the most nodes.
Recursion · Coding Question
Recursively generate every outcome of rolling n dice with m faces each.
Recursion · Coding Question
Find every combination of candidates that sums to a target, reusing numbers as often as you like (LeetCode #39). Asked at Amazon, Airbnb and 19 more companies.
