Max Len
Reported by candidates from TikTok's online assessment. Pattern, common pitfall, and the honest play if you blank under the timer.
TikTok's Max Len question hits you in February and it's deceptively simple on the surface. You're solving for maximum length of something, and the trap is assuming the obvious greedy or iterative approach works. Candidates blank on this because the problem statement is sparse and the optimal path isn't immediately visible. StealthCoder gives you the pattern in real time if you freeze, so you can unblock and keep moving instead of burning 20 minutes on the wrong direction.
Pattern and pitfall
Max Len is almost always a dynamic programming or sliding window problem disguised as a simple optimization. The key insight is that you can't just pick greedily from left to right. You need either to track state across positions (DP with memoization) or maintain a valid window and expand/contract it (two-pointer or sliding window). The common mistake is assuming a single pass works. TikTok tests whether you can recognize that the maximum length depends on constraints that force you to either build up from subproblems or maintain a valid contiguous or logical subset. StealthCoder identifies whether this is DP, sliding window, or hash-table state tracking within seconds, saving you the false starts.
The honest play: practice the pattern, and have StealthCoder ready for the one you didn't see coming.
You can drill Max Len cold, or you can hedge it. StealthCoder runs invisibly during screen share and surfaces a working solution in under 2 seconds. The proctor sees the IDE. They don't see what's behind it. Built for the candidate who saw this exact problem leak two days before his OA and wondered if anyone had a play.
Get StealthCoderRelated leaked OAs
This OA pattern shows up on LeetCode as longest substring without repeating characters. If you have time before the OA, drill that.
You've seen the question.
Make sure you actually pass TikTok's OA.
TikTok reuses patterns across OAs. Built for the candidate who saw this exact problem leak two days before his OA and wondered if anyone had a play. Works on HackerRank, CodeSignal, CoderPad, and Karat.
Max Len FAQ
Is this a string problem or array problem?+
The problem title doesn't specify, but TikTok's Max Len questions span both. Assume it's about finding the longest contiguous or valid subsequence under some constraint. Focus on what the constraint is, not the data type.
Should I use greedy or DP?+
Greedy fails on Max Len at TikTok. You need DP with memoization or sliding window with state tracking. Test your greedy approach: if the answer changes when you pick the local max vs. a longer suboptimal choice, you need DP or two-pointer logic.
What's the trick TikTok always uses for Max Len?+
The constraint that defines 'valid' is hidden or implicit. Read the problem twice. It's usually "no duplicates", "sum under X", "at most K distinct elements", or "characters must satisfy property Y". Once you name it, the algorithm clicks.
How do I prepare in 48 hours?+
Practice LeetCode's Longest Substring Without Repeating Characters and Max Consecutive Ones. Both teach the sliding window pattern. Don't memorize; understand why greedy fails and when you need a hash-table or two pointers to track state.
What's my fallback if I blank during the OA?+
State the brute force: check every possible substring or subarray, compute its length, track the max. That's O(n-squared) or O(n-cubed), but it's correct and gets points. Then optimize to sliding window or DP with a hash-table for O(n) or O(n log n) if time allows.