Find the Sum of Subsequence Powers
A hard-tier problem at 23% community acceptance, tagged with Array, Dynamic Programming, Sorting. Reported in interviews at Rubrik and 0 others.
Find the Sum of Subsequence Powers is a hard problem that hits the intersection of arrays, dynamic programming, and sorting. It's asked at companies like Rubrik, and with a 23% acceptance rate, most candidates who attempt it don't solve it cleanly. The trick isn't obvious from the problem statement alone. You either see the pattern or you don't. If this lands in your OA and the approach doesn't click in the first five minutes, StealthCoder runs invisibly during your assessment and surfaces a working solution in seconds, no proctor detection.
Companies that ask "Find the Sum of Subsequence Powers"
Find the Sum of Subsequence Powers 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 problem demands you recognize that sorting the array first unlocks a DP structure that's otherwise buried. Once sorted, the pattern becomes clear: use dynamic programming to track subsequence states and compute their powers efficiently. Most candidates try to brute-force all subsequences or miss that the power calculation depends on specific properties of the sorted order. Common pitfall: attempting the problem without sorting leads to exponential complexity with no pruning. The DP state often involves tracking the last element picked and the length of the subsequence built so far. Overflow and modulo arithmetic also trip people up. If you hit this live and the DP transition doesn't click, StealthCoder has the exact state definition and transition logic ready.
Pattern tags
You know the problem.
Make sure you actually pass it.
Find the Sum of Subsequence Powers recycles across companies for a reason. It's hard-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.
Find the Sum of Subsequence Powers interview FAQ
Is this problem actually asked at major companies?+
Only Rubrik appears in reports asking this. That said, it's a hard-tier array plus DP problem, so it fits the pattern of problems at companies that dig into optimization. The 23% acceptance rate is a signal this one weeds people out.
What's the main trick I'm missing if I can't solve it?+
Sort the array first. Sorting unlocks the DP structure because the power of a subsequence has a dependency on element order or distance. Without sorting, you're left with exponential exploration. Once sorted, DP transitions become tractable.
How does sorting relate to the DP?+
After sorting, the problem often becomes: what is the best subsequence to pick such that some power function is maximized or summed. Sorting collapses the search space because you process candidates in a fixed order, making DP states smaller and transitions computable in polynomial time.
What DP state should I track?+
Common states are dp[i][length] or dp[i][last_element], where i is the current index in the sorted array and length tracks the size of the subsequence built so far. The power is then a function of the elements in that subsequence, derived from the sorted order.
What catches people on this problem in a real OA?+
Modulo arithmetic, integer overflow on large powers, and forgetting to handle edge cases like empty subsequences. The time pressure also kills submissions: people jump to DP without sorting first and waste 20 minutes on a dead-end approach.
Want the actual problem statement? View "Find the Sum of Subsequence Powers" on LeetCode →