ZScaler coding interview
questions, leaked.
24 problems reported across recent ZScaler interviews. Top patterns: array, hash table, string. The list below is what most reported candidates actually saw, plus the honest play if you can't grind all of it.
Zscaler's coding rounds hit you with 24 problems split across easy, medium, and hard. The distribution is punishing: arrays dominate with 14 problems, hash tables with 10, and strings, math, and bit manipulation sprinkled throughout. You'll see Two Sum and Jump Game alongside harder pattern problems like Maximum Strong Pair XOR II and Word Ladder. Most candidates waste time drilling every topic evenly. The real move is knowing that arrays and hash tables account for over half the ask, then using StealthCoder as your safety net if you blank on a bit-manipulation or DP problem mid-assessment.
Top problems at ZScaler
| # | Problem | Diff | Frequency | Pass % | Patterns |
|---|---|---|---|---|---|
| 01 | Apply Operations to Make Sum of Array Greater Than or Equal to k | MEDIUM | 100.0 | 43% | Math · Greedy · Enumeration |
| 02 | Day of the Year | EASY | 100.0 | 48% | Math · String |
| 03 | Largest Number After Digit Swaps by Parity | EASY | 100.0 | 64% | Sorting · Heap (Priority Queue) |
| 04 | Maximum Strong Pair XOR I | EASY | 100.0 | 75% | Array · Hash Table · Bit Manipulation |
| 05 | Maximum Strong Pair XOR II | HARD | 100.0 | 31% | Array · Hash Table · Bit Manipulation |
| 06 | Optimal Account Balancing | HARD | 94.4 | 50% | Array · Dynamic Programming · Backtracking |
| 07 | Robot Bounded In Circle | MEDIUM | 77.1 | 56% | Math · String · Simulation |
| 08 | Jump Game | MEDIUM | 69.9 | 39% | Array · Dynamic Programming · Greedy |
| 09 | Two Sum | EASY | 69.9 | 56% | Array · Hash Table |
| 10 | Rotate Image | MEDIUM | 69.9 | 78% | Array · Math · Matrix |
| 11 | Find the Smallest Divisor Given a Threshold | MEDIUM | 69.9 | 64% | Array · Binary Search |
| 12 | Minimum Increment to Make Array Unique | MEDIUM | 59.8 | 60% | Array · Greedy · Sorting |
| 13 | Word Ladder | HARD | 59.8 | 43% | Hash Table · String · Breadth-First Search |
| 14 | Number of Divisible Triplet Sums | MEDIUM | 59.8 | 68% | Array · Hash Table |
| 15 | Degree of an Array | EASY | 59.8 | 57% | Array · Hash Table |
| 16 | Longest Substring Without Repeating Characters | MEDIUM | 59.8 | 37% | Hash Table · String · Sliding Window |
| 17 | Moving Average from Data Stream | EASY | 59.8 | 80% | Array · Design · Queue |
| 18 | Remove Duplicates from Sorted Array | EASY | 59.8 | 60% | Array · Two Pointers |
| 19 | Linked List Cycle | EASY | 59.8 | 53% | Hash Table · Linked List · Two Pointers |
| 20 | Longest Common Prefix | EASY | 59.8 | 45% | String · Trie |
| 21 | Search in Rotated Sorted Array | MEDIUM | 59.8 | 43% | Array · Binary Search |
| 22 | Contains Duplicate | EASY | 59.8 | 63% | Array · Hash Table · Sorting |
| 23 | Palindrome Linked List | EASY | 59.8 | 56% | Linked List · Two Pointers · Stack |
| 24 | LRU Cache | MEDIUM | 59.8 | 45% | Hash Table · Linked List · Design |
Frequencies derived from public community-tagged interview reports. Click a row to view on LeetCode.
You have a week, maybe less. You can't out-grind the list above. StealthCoder runs invisibly during the actual ZScaler OA. The proctor cannot see it. Screen share cannot detect it. Made by a working Amazon engineer who got tired of watching qualified friends bomb OAs they'd solve cold in an IDE.
Get StealthCoder- array14 · 58%
- hash table10 · 42%
- string5 · 21%
- math4 · 17%
- greedy3 · 13%
- sorting3 · 13%
- bit manipulation3 · 13%
- sliding window3 · 13%
- two pointers3 · 13%
- linked list3 · 13%
The data reveals a company that tests breadth but expects mastery in two core areas. Array problems (14 total) range from simple degree-of-array lookups to complex XOR manipulation problems. Hash tables (10) appear almost always paired with arrays, signaling you'll need fast lookups under time pressure. Everything else is secondary. Math and greedy pop up in problems like Apply Operations to Make Sum of Array Greater Than or Equal to k and Minimum Increment to Make Array Unique, but they're low-frequency escape valves. The three hard problems (Maximum Strong Pair XOR II, Optimal Account Balancing, Word Ladder) test whether you can combine multiple patterns simultaneously. Easy problems are roughly half the set, so don't skip them on test day. If you hit an unfamiliar pattern mid-OA, StealthCoder surfaces a working solution in seconds while the proctor sees nothing.
Companies with similar patterns
If you prepped for ZScaler, these companies recycle ~60% of the same topics.
You've seen the list.
Now make sure you pass ZScaler.
Memorizing every problem above in a week is a fantasy. StealthCoder is the hedge: an AI overlay that's invisible during screen share. It reads the problem on screen and surfaces a working solution in under 2 seconds. Made by a working Amazon engineer who got tired of watching qualified friends bomb OAs they'd solve cold in an IDE. Works on HackerRank, CodeSignal, CoderPad, and Karat.
ZScaler interview FAQ
How many array and hash-table problems should I solve before the interview?+
Zscaler's data shows 14 array and 10 hash-table problems across their known set. Treat these as non-negotiable. Drill at least 20-25 mixed array/hash problems, prioritizing Two Sum, Degree of an Array, and Minimum Increment to Make Array Unique as warm-ups. That covers your confident ground.
Is bit manipulation really necessary for Zscaler?+
Yes, but context matters. Three problems explicitly require it: Maximum Strong Pair XOR I and II plus Optimal Account Balancing. However, XOR problems can be harder than they look. Don't waste a week on bit tricks. Solve the XOR problems once, then move on. That's your floor.
What's the hardest topic to prepare for in one week?+
Optimal Account Balancing combines DP, backtracking, and bitmask. It's rare and brutal. Word Ladder (BFS) is also non-obvious. You likely won't see them, but if you do and you're stuck, you need a backup plan. That's where preparation meets reality.
Should I study math problems or skip them?+
Four math problems appear in the data, but they're usually paired with greedy or strings. Day of the Year is straightforward date math. Apply Operations is enumeration-heavy. Spend 2-3 hours on math if you're weak, otherwise prioritize arrays and hash tables first.
How do I allocate study time across difficulty levels?+
The set is roughly 46% easy, 42% medium, 12% hard. Easy problems are fast confidence builders. Spend 40% of prep time on easy/medium hybrids, 40% on medium/hard combos, 20% on understanding hard problem patterns. Don't get stuck on one hard problem for hours.