Redis Coding Interview Questions
25 Redis coding interview problems with full optimal solutions — 8 easy, 12 medium, 5 hard. Every problem ships with multiple approaches (brute-force first, then the optimal), complexity tables for each, company-specific tips on what an Redis interviewer values, and a FAQ section.
Showing 8 problems of 25
- #1easyfoundational
1. Two Sum
Find two indices whose values sum to a target; the canonical hash-map warmup at Redis where interviewers probe your fluency with O(1) lookups.
- #2easyfoundational
2. Best Time to Buy and Sell Stock
Find the maximum profit from one buy-sell transaction over a price stream, a warm-up Redis uses to gauge single-pass thinking.
- #3easyfoundational
3. Single Number
Find the one element that appears once when every other appears twice; Redis uses it to probe XOR-trick fluency relevant to bitmap operations.
- #4easyfoundational
4. Majority Element
Find the element that appears more than n/2 times; Redis interviewers use it to test Boyer-Moore voting, a constant-space pattern that maps onto stream-processing.
- #5easyfoundational
5. Reverse Linked List
Reverse a singly linked list in place; Redis uses it as a warm-up before diving into Redis list internals like the quicklist and listpack.
- #6easyfoundational
6. Invert Binary Tree
Mirror a binary tree in place; Redis screens with this to confirm clean recursion and traversal hygiene before discussing skiplist traversal.
- #7easyfoundational
7. Diameter of Binary Tree
Find the longest path between any two nodes; Redis uses it to gauge post-order recursion which mirrors how the engine walks command call trees.
- #8easyfoundational
8. Binary Search
Implement classic binary search on a sorted array; Redis uses it to confirm log-time intuition before discussing skiplist random-level shortcuts.