Reformat Date
A easy-tier problem at 67% community acceptance, tagged with String. Reported in interviews at Celigo and 4 others.
Reformat Date looks trivial until you're live in an assessment and blank on the month-name mapping. It's asked by Celigo, Twilio, Veritas, Expedia, and Goldman Sachs. The problem wants you to convert a date string from one format to another, usually involving month names. With a 67% acceptance rate, this should be a gimme, but the catch is the month lookup and string parsing need to be exact. If you haven't drilled the month-index pairing or fumble the substring boundaries under pressure, you'll burn time debugging. StealthCoder solves it in seconds invisible to the proctor if you blank.
Companies that ask "Reformat Date"
Reformat Date 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 a senior engineer who knows the OA is theater. This is the script.
Get StealthCoderThe trick is simple: store the month names in a list or map, parse the input string to extract day, month name, and year, then look up the month's 2-digit index and reassemble into the target format. Most candidates either mess up the month mapping (off-by-one errors with 0-indexing), parse the wrong substrings, or forget to pad single-digit days with a leading zero. The obvious approach works fine here, there's no hidden DP or graph trick, but the execution has small gotchas that multiply under exam stress. String manipulation is the only topic, and at easy difficulty it's about care and testing, not cleverness. StealthCoder is the hedge if you zone out on edge cases in the live assessment and need a clean, tested solution on the spot.
Pattern tags
You know the problem.
Make sure you actually pass it.
Reformat Date recycles across companies for a reason. It's easy-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 a senior engineer who knows the OA is theater. This is the script. Works on HackerRank, CodeSignal, CoderPad, and Karat.
Reformat Date interview FAQ
Is Reformat Date still asked at big tech?+
Yes. Celigo, Twilio, Veritas, Expedia, and Goldman Sachs report it. At easy difficulty and 67% acceptance, it's a screening problem. Companies use it to filter careless candidates. Pass it clean and you move on.
What's the actual trick?+
There isn't one. Parse the input string to pull day, month name, and year. Map the month name to its 2-digit index (usually 01-12). Reassemble in the target format. The trap is substring boundaries and zero-padding. Test with single-digit days.
What do I need to know about String as a topic?+
For this problem, string operations are basic: substring extraction, character iteration, and concatenation. No regex is needed. You're just splitting and rebuilding. The real skill is attention to detail and testing edge cases in your head before code.
How long should this take?+
If you know the month names and write clean parsing logic, 3 to 5 minutes. If you second-guess the month index or forget padding rules, 10 to 15. Under live pressure, mistakes stack. That's when StealthCoder's invisible solution saves you.
Should I memorize month mappings?+
No. Hard-code a list or dictionary in your solution. The problem expects it. Every language supports this. The skill being tested is parsing and string manipulation, not your memory of calendar order.
Want the actual problem statement? View "Reformat Date" on LeetCode →