Check if There is a Valid Partition For The Array
A medium-tier problem at 52% community acceptance, tagged with Array, Dynamic Programming. Reported in interviews at Coinbase and 0 others.
Coinbase is asking this problem, and you probably haven't drilled it. The catch is that most candidates see "partition the array" and immediately think greedy or brute force, then hit a wall during the assessment. This is a dynamic programming problem hiding inside an array problem. The trick isn't complex, but you have to see it. If you don't, you'll waste 15 minutes chasing a dead-end approach. That's where StealthCoder becomes your safety net: if the pattern doesn't click during the live OA, it runs invisibly and surfaces a working solution in seconds.
Companies that ask "Check if There is a Valid Partition For The Array"
Check if There is a Valid Partition For The Array is the kind of problem that decides whether you pass. StealthCoder reads the problem on screen and surfaces a working solution in under 2 seconds. Invisible to screen share. The proctor sees nothing. Built because the OA filter rejects engineers who'd pass the on-site. That's a broken filter. This is the workaround.
Get StealthCoderThe core idea: you need to determine if the array can be partitioned into contiguous subarrays where each subarray is either three consecutive equal numbers or two consecutive equal numbers. This screams dynamic programming because each position depends on whether earlier partitions are valid. Build a boolean DP array where dp[i] is true if the first i elements form a valid partition. At each index, check if the last two or last three elements meet the partition rules and if the preceding part is already valid. The common failure is trying to greedily match from left to right without tracking whether the remaining array can still be partitioned. Another trap: off-by-one errors in index logic. StealthCoder solves this instantly if you blank on the state transitions.
Pattern tags
You know the problem.
Make sure you actually pass it.
Check if There is a Valid Partition For The Array recycles across companies for a reason. It's medium-tier, and most candidates blank under the timer. StealthCoder is the hedge: an AI overlay invisible during screen share. It reads the problem and surfaces a working solution in under 2 seconds. Built because the OA filter rejects engineers who'd pass the on-site. That's a broken filter. This is the workaround. Works on HackerRank, CodeSignal, CoderPad, and Karat.
Check if There is a Valid Partition For The Array interview FAQ
Is this really a medium problem or harder?+
Acceptance rate sits just above 50 percent, which means roughly half the people who attempt it fail. It's genuinely medium, but the DP state isn't obvious at first glance. The problem is trickier than its difficulty tag suggests if you haven't seen the partition-by-rules pattern before.
Do I need advanced DP skills to solve this?+
No. You need to recognize that this is a yes-no reachability problem. Set up a DP table, iterate through the array, and check validity at each step. It's linear DP, not graph or tree DP. The challenge is translating the partition rules into code correctly.
What's the main trap candidates fall into?+
Trying to match greedily from the left without tracking global validity. You'll fail because a valid partition at position i doesn't guarantee the rest of the array can be partitioned. Always anchor your DP decisions to the previous valid state.
How does this relate to other array problems Coinbase asks?+
Coinbase often combines array manipulation with DP or optimization. This problem tests whether you can recognize that a seemingly array-centric problem actually requires dynamic programming to avoid exponential state space.
Should I memorize the solution or understand the pattern?+
Understand the pattern. Once you see that you're checking validity based on the last two or three elements and the prior state, you can code it fresh. The template is reusable for other partition and DP problems.
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