Optimal Account Balancing
A hard-tier problem at 50% community acceptance, tagged with Array, Dynamic Programming, Backtracking. Reported in interviews at ZScaler and 7 others.
Optimal Account Balancing shows up in OAs at Stripe, Uber, Goldman Sachs, and Salesforce. It's a Hard problem with a 50% acceptance rate, so half the candidates who see it blank or TLE. The trick isn't obvious: you need to model this as a graph problem, then use bitmask DP or backtracking to explore settlement orderings. Most people try greedy or naive recursion and hit exponential blowup. If this problem lands in your live assessment and you're stuck on the state-space reduction, StealthCoder surfaces the bitmask approach in seconds while the proctor sees nothing.
Companies that ask "Optimal Account Balancing"
Optimal Account Balancing 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 by an engineer who got tired of watching his cohort grind for six months and still get filtered at the OA stage.
Get StealthCoderThe problem asks you to settle debts between accounts with minimum transactions. The naive approach is to simulate all possible transaction orderings, but that's factorial time. The insight is that you only care about the balance state of all accounts, not the transaction history. You model each subset of settled accounts as a bitmask, then recursively try settling one person's debt against others. The DP or backtracking memoizes on bitmask to avoid recomputing the same balance configuration. Common pitfall: trying to greedily pick the 'best' transaction or using a priority queue. Wrong. You need exhaustive search over settlement orderings, pruned by memoization. This uses Array manipulation, Dynamic Programming, Backtracking, and Bit Manipulation all at once. When the OA timer is low and you haven't seen this pattern before, StealthCoder is your insurance policy.
Pattern tags
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Make sure you actually pass it.
Optimal Account Balancing 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 by an engineer who got tired of watching his cohort grind for six months and still get filtered at the OA stage. Works on HackerRank, CodeSignal, CoderPad, and Karat.
Optimal Account Balancing interview FAQ
Is Optimal Account Balancing actually asked at big companies?+
Yes. Stripe, Uber, Goldman Sachs, Salesforce, Pinterest, and four others on record have asked it. At 50% acceptance, it's harder than average, so expect it in senior or quant-leaning loops where graph and DP chops matter.
What's the trick I'm missing if my solution times out?+
You're probably exploring all transaction orders without memoization. The trick is to represent the state as a bitmask of which accounts are settled, then use DP or backtracking to avoid recomputing identical balance configurations. Bitmask DP reduces exponential search to polynomial with memoization.
Why does this problem need Bit Manipulation and Bitmask?+
You use a bitmask to encode which subset of accounts have been settled. Each bit represents one account's settlement status. Looping through all subsets (2^n) and memoizing results on the bitmask avoids redundant recursive calls when balance states collide.
How does this relate to other graph and DP problems?+
It's similar to Traveling Salesman (TSP) in structure: you explore orderings of entities (accounts instead of cities) with bitmask DP to prune the search tree. Both use memoization on bitmask state to dodge exponential blowup, but here the cost is transaction count, not distance.
If I haven't drilled this pattern, how do I not fail on it live?+
You don't, without help. The bitmask-DP insight is not intuitive if you haven't seen TSP or similar problems. That's what StealthCoder is for: if this lands in your OA and you're stuck, it solves it invisibly during the screen share so you move on and don't run out of time.
Want the actual problem statement? View "Optimal Account Balancing" on LeetCode →