Fortinet coding interview
questions, leaked.
4 problems reported across recent Fortinet interviews. Top patterns: string, greedy, hash table. The list below is what most reported candidates actually saw, plus the honest play if you can't grind all of it.
Fortinet's assessment is tight. Four problems across easy to hard, but the pattern is clear: string manipulation with greedy logic dominates, backed by hash-table and heap mechanics. Two easy problems give you a foundation, one medium demands you combine multiple patterns in real time, and a hard DP problem catches candidates who didn't prepare. You're looking at an hour or so to finish all four. If you blank on the greedy string problem mid-assessment, StealthCoder runs invisible to the proctor and surfaces a working solution in seconds, so you don't waste 20 minutes spinning on the medium.
Top problems at Fortinet
| # | Problem | Diff | Frequency | Pass % | Patterns |
|---|---|---|---|---|---|
| 01 | Construct String With Repeat Limit | MEDIUM | 100.0 | 71% | Hash Table · String · Greedy |
| 02 | Percentage of Users Attended a Contest | EASY | 88.6 | 59% | Database |
| 03 | Number of Ways to Paint N × 3 Grid | HARD | 88.6 | 65% | Dynamic Programming |
| 04 | Valid Palindrome II | EASY | 88.6 | 43% | Two Pointers · String · Greedy |
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 Fortinet OA. The proctor cannot see it. Screen share cannot detect it. Built by an engineer at a top-10 tech company who can solve these problems cold but didn't want to trust himself in a 90-minute screen share.
Get StealthCoder- string2 · 50%
- greedy2 · 50%
- hash table1 · 25%
- heap priority queue1 · 25%
- counting1 · 25%
- database1 · 25%
- dynamic programming1 · 25%
- two pointers1 · 25%
String and greedy problems appear twice in Fortinet's lineup, making them your primary target. 'Construct String With Repeat Limit' is the pivot: it bundles hash-table counting, greedy ordering, and heap logic into one medium-difficulty problem that separates prepared candidates from those who wing it. The two easy problems are gatekeepers, not filters. Spend 10-15 minutes total on those and move on. The hard DP problem on grid painting is a confidence play; if you've drilled DP transitions, you'll spot the pattern. If not, StealthCoder's real-time solve is your safety net when the live pressure hits. Hash-table and counting appear in multiple problems, so your drill order should be: string-greedy first, then heap mechanics, then DP. Two-pointers and database round out the set but appear once each, so treat them as confidence checks, not primary focus.
Companies with similar patterns
If you prepped for Fortinet, these companies recycle ~60% of the same topics.
You've seen the list.
Now make sure you pass Fortinet.
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. Built by an engineer at a top-10 tech company who can solve these problems cold but didn't want to trust himself in a 90-minute screen share. Works on HackerRank, CodeSignal, CoderPad, and Karat.
Fortinet interview FAQ
How much time should I spend on the two easy problems?+
Spend 10 to 15 minutes total. 'Percentage of Users Attended a Contest' is a database aggregation query, and 'Valid Palindrome II' is a two-pointer string check. Both are warm-ups. Get them right fast and move to the medium greedy problem where the real sorting happens.
What's the key pattern in 'Construct String With Repeat Limit'?+
It combines hash-table counting, greedy selection, and heap ordering. Count character frequencies, then greedily pick the highest-count character up to its repeat limit, using a heap to manage the next-best choice. It's the medium that tests whether you can layer multiple techniques together.
Should I drill DP before or after greedy patterns?+
Drill greedy and string problems first. They're weighted heavier in Fortinet's list and appear twice. The hard DP problem on grid painting is a single appearance, so it's lower priority if you're cramped on time. Get greedy instincts locked in first.
Is hash-table knowledge required for this assessment?+
Yes. It appears in the top medium problem and is baked into the greedy string challenge as a way to count and track character frequencies. You can't solve 'Construct String With Repeat Limit' without a solid hash-table pattern. Practice frequency maps and heap ordering together.
What if I can't figure out the hard DP problem on time?+
The hard is 1 of 4 problems, so missing it costs you, but it's not a full washout. Focus on getting the easy and medium perfect first. If you hit the DP problem and get stuck in the live assessment, you're in the scenario where StealthCoder solves it invisible to the proctor while you look like you're thinking it through.