Find the Sum of the Power of All Subsequences
A hard-tier problem at 37% community acceptance, tagged with Array, Dynamic Programming. Reported in interviews at DE Shaw and 0 others.
DE Shaw is asking this problem, and at 37% acceptance you're looking at a legitimately hard DP pattern that trips up most candidates on a live OA. The trick isn't just summing subsequence powers; it's recognizing that you can't enumerate all 2^n subsequences and must instead use coefficient DP to track contributions. Most people start building recursion trees and run out of time before they realize each element contributes to the answer in a mathematically predictable way. If this problem shows up during your assessment and you blank on the insight, StealthCoder surfaces the working solution invisible to the proctor.
Companies that ask "Find the Sum of the Power of All Subsequences"
Find the Sum of the Power of All Subsequences 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. Made by a working Amazon engineer who got tired of watching qualified friends bomb OAs they'd solve cold in an IDE.
Get StealthCoderThe problem asks you to compute the sum of element powers across all possible subsequences of an array. Naive enumeration fails immediately since subsequence count is exponential. The real pattern: use dynamic programming to track how many times each element appears in a subsequence of a given length, then multiply by its power contribution. You're essentially counting subsets and weighting them by the power formula, not iterating subsets. The common pitfall is treating it like a subset sum problem and trying backtracking; instead you need coefficient tracking. Array and Dynamic Programming topics align perfectly here because you're building up contributions element-by-element while maintaining counts. StealthCoder is the safety net when the exponential bluff catches you during the assessment; it handles the DP table construction in seconds.
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Find the Sum of the Power of All Subsequences 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. 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.
Find the Sum of the Power of All Subsequences interview FAQ
Is this problem really as hard as the 37% acceptance suggests?+
Yes. The 37% pass rate reflects that most candidates don't immediately see the coefficient DP angle and waste time on exponential approaches. Once you recognize you're counting contributions rather than enumerating, the solution clicks. But on a live OA with time pressure, that click often doesn't happen.
What makes this different from standard subset DP problems?+
Subset DP usually asks you to find one optimal subset or count subsets meeting a condition. This asks you to sum values across all subsets using a power formula. That shift from 'find a subset' to 'aggregate across all subsets with a weight' catches people who've drilled standard DP patterns.
Do I need to optimize space if the array is large?+
The problem doesn't specify constraints, so assume worst-case and plan for space-efficient DP. Rolling arrays or careful state management matter when you're tracking counts across all subsequence lengths. This is where implementation details separate a 30-minute solve from a 90-minute debugging spiral.
How does the power function change the approach?+
The power formula defines the weight contribution of each element based on subsequence position or count. This isn't arbitrary; it usually ties to combinatorics. You must precompute or calculate powers efficiently so they don't become a bottleneck during the DP loop.
Will practicing other Array and Dynamic Programming problems prepare me?+
Partially. Standard DP and subsequence problems build intuition, but this one requires the specific insight of coefficient DP and contribution tracking. Drills help, but if you hit this live and haven't seen the pattern, that's exactly when StealthCoder becomes your hedge.
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