Largest Time for Given Digits
A medium-tier problem at 36% community acceptance, tagged with Array, String, Backtracking. Reported in interviews at LiveRamp and 0 others.
You're given four digits and asked to form the largest valid time in HH:MM format. Sounds simple until you realize there's no greedy path. The digits 2, 3, 5, 9 can't form any valid time at all. LiveRamp asked this one, and the 35% acceptance rate isn't a coincidence. The trick lives in backtracking through permutations and validating hour/minute constraints on the fly. If this lands on your OA and you freeze on the constraint logic, StealthCoder solves it in seconds, invisible to the proctor.
Companies that ask "Largest Time for Given Digits"
Largest Time for Given Digits 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 at a top-10 tech company who can solve these problems cold but didn't want to trust himself in a 90-minute screen share.
Get StealthCoderThe naive approach fails fast: you can't sort the digits descending and hope. Hours cap at 23, minutes at 59, and not every digit combination produces a valid time. The right move is enumerate all 24 permutations of the four digits, treat the first two as hours and the last two as minutes, validate both, and track the maximum valid time found. Backtracking here means trying each permutation in descending order to short-circuit once you hit a valid result, though enumeration-only also works under the time budget. The real friction point is candidates overthinking optimizations when brute force through all 24 permutations is the intended path. StealthCoder hedges the candidate who didn't drill Backtracking or Enumeration patterns and hits this live.
Pattern tags
You know the problem.
Make sure you actually pass it.
Largest Time for Given Digits recycles across companies for a reason. It's medium-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 at a top-10 tech company who can solve these problems cold but didn't want to trust himself in a 90-minute screen share. Works on HackerRank, CodeSignal, CoderPad, and Karat.
Largest Time for Given Digits interview FAQ
Is this a hard backtracking problem?+
No. It's backtracking in name only because you permute a tiny set. The actual work is validating 24 candidate times. Most candidates stumble on the constraint logic or overthink optimization. The acceptance rate is low because people second-guess the brute-force approach.
What's the trick to avoid invalid times?+
Check hours against 23 and minutes against 59 immediately after assigning positions. Don't try to filter digits up-front. Iterate all 24 permutations, validate, and track the max. No clever preprocessing saves time.
How do I return the answer in the right format?+
Format as 'HH:MM' using zero-padded strings. Example: hours 5, minutes 9 becomes '05:09'. If no valid time exists, return empty string. Read the problem statement carefully for edge cases.
Does Array, String, Backtracking, Enumeration mean I need all four?+
You'll use String for formatting, Enumeration or Backtracking for permutations, and Array as the input container. All four topics touch the solution. Focus on the enumeration loop and constraint checks, not the taxonomy.
Is LiveRamp the only company asking this?+
According to available data, yes, one company is reported. That doesn't mean others aren't asking it. The 35% acceptance rate suggests it's hard enough to be a real filter question in assessments.
Want the actual problem statement? View "Largest Time for Given Digits" on LeetCode →