Turing.com Online Assessment Algorithm Question Experience
Question Details
Problem Statement Given a string num consisting of digits and an integer k, reorder the digits to form the lexicographically largest valid string. A string is considered valid if no specific d
Full Details
Problem Statement Given a string num consisting of digits and an integer k, reorder the digits to form the lexicographically largest valid string. A string is considered valid if no specific digit appears consecutively more than k times. The goal is to maximize the value of the resulting number using the available digit frequencies.
Constraints * $1 \le k \le \text{num.length} \le 10^7$ * num consists exclusively of digits 0 through 9.
Approach The problem requires a greedy strategy to ensure the number is as large as possible. 1.
Frequency Count: Calculate the frequency of every digit (0-9) present in the input string. 2.
Greedy Construction: Iterate through the digits from largest (9) to smallest (0). * Append the current largest available digit to the result string up to k times, or until its count reaches zero. * If the limit k is reached but instances of the current digit still remain, a "separator" digit is required to break the sequence. * Identify the next largest available digit to serve as this separator. Append it once to the result and decrement its count. *
Return to the primary largest digit and continue appending. 3.
Termination: If the current largest digit has reached the consecutive limit k and no smaller digits are available to act as separators, the construction ends.
Examples *
Input: num = "3391933", k = 3 *
Output: "9933313" *
Logic: The largest digits (9s) are placed first. The 3s are placed next, but limited to a streak of three. The 1 is used as a separator, allowing the final 3 to be placed. *
Input: num = "1121212", k = 2 *
Output: "221211" *
Logic: The 2s are prioritized. After two 2s, a 1 is used as a separator. This pattern continues until no separators remain to accommodate the final 1.
About This Question
This is a reported interview question from a turingcom interview for a swe role during the oa round reported in 2025.
About Turingcom Interview Reports
This question was reported by a candidate who interviewed at Turingcom. LeakCode aggregates interview reports from 10+ sources, including 1Point3Acres, Glassdoor, LeetCode Discuss, Blind, Reddit, Indeed, and Nowcoder. Each report is translated where necessary, deduplicated against existing entries, and tagged by company, role, round type, and reporting date.
Use this question as one calibration data point, not a memorization target. Companies typically rotate their question pools every 2-4 months; the exact wording of a 2024 question may differ from what you encounter today. The underlying pattern, difficulty level, and follow-up depth at Turingcom are the higher-signal extractions to take from this report.
For broader preparation context, the Turingcom interview process typically includes a recruiter screen, one or two technical phone screens, and a 4-5 round on-site loop covering coding, system design (at L4+ levels), and behavioral. Reports tagged on LeakCode show the round-by-round distribution and typical difficulty calibration. To browse questions filtered by round type and seniority, use the company hub linked above.
How To Practice This Type of Question
Solve similar problems on LeetCode under timed conditions (25-35 minutes per medium difficulty). The goal is pattern recognition: recognize the underlying technique (sliding window, two-pointer, BFS, memoized recursion, etc.) within 60-90 seconds of reading. Strong candidates verbalize their hypothesis out loud before coding, then iterate based on feedback. Weak candidates dive into implementation immediately, lose time on the wrong approach, and run out of time for follow-ups.
Companies update their question pools every 2-4 months. The exact wording of any given question may have been retired by the time you interview. Focus your prep on the pattern, not the specific problem. The patterns that appear in Turingcom reports consistently are the ones worth investing in; one-off niche problems are not.
During Your Turingcom Round
Apply the standard interview round template: clarify requirements (2-3 minutes), state your approach out loud and confirm direction with the interviewer (3-5 minutes), code with narration (15-25 minutes), test with concrete examples including edge cases (5 minutes), discuss optimization or trade-offs if time permits (5 minutes). This template is universally accepted across FAANG and adjacent companies; deviating from it produces weaker interviewer feedback signal.
The single most predictive failure mode in Turingcom reports tagged "no hire": not asking clarifying questions. Interviewers are explicitly trained to weight this. Strong candidates ask 3-5 clarifying questions even on problems that look obvious; weak candidates dive into code immediately. The clarifying-question check is often the first signal recorded in the interviewer's written notes.