Citadel / Citadel Securities Interview Question Bank
Citadel and Citadel Securities run two distinct loops sharing one brand. Citsec (the market maker) hires for HFT software, quant research and quant dev; its phone screens lean on small, sharp coding prompts (merge-K, ring buffers, stock-DP ladders) and the loop is famously single-fail — any weak round and the next interview is cancelled within a day. Citadel (the hedge fund) and its sub-orgs (GQS, EQR, NXT) lean harder on probability brainteasers, deep resume drilling and a multi-week team-match stage where coding bar drops but cultural and PM-style fit dominates the offer decision.
39
questions
Last updated
Before you start
Showing 39 of 39
In-Memory Spreadsheet with Arithmetic FormulasTerminal-Based Two-Player BattleshipPossible MEX Values After At Most One IncrementPermutation-Invariant Classification of Variable-Length Feature SetsMerge Timestamped Price-Delta FeedsReconcile Unmatched Buy and Sell TradesMinimum Changes for Palindromic Password BlocksMaximize Earnings by Converting Days OffDesign an Order Book with Exchange BBO and NBBOMinimum Changes to Make Every Block a PalindromeMaximize Earnings by Converting Days Off to WorkdaysMinimum Changes for Every Length-K Substring to Be a PalindromeMaximum Earnings with Workday ChangesMinimum Replacements for Palindromic Fixed-Size BlocksMaximize Income by Converting Rest DaysMinimum Changes for a Palindromic Periodic PasswordMaximize Earnings by Converting Days OffMinimum Changes to Make Every Block a PalindromeMaximize Earnings by Converting Days Off to WorkdaysContent-Deduplicating File SystemSearch Suggestions SystemMinimum Changes to Make Every Password Block a PalindromeMaximize Earnings by Converting Days OffMinimum Changes to Make Password Blocks PalindromicMaximize Earnings by Converting Days OffMinimum Character Changes for Palindromic Password BlocksMaximize Earnings by Converting Days Off to WorkdaysMinimum Changes for Block Palindrome PasswordMaximum Earnings After Converting Days OffMinimum Changes for a Palindromic Periodic Password