Mercor coding interview

Round 3 of 5 · 5 questions reported

Length: 45 min
Format: Live coding
Heads-up: Reported onsite problems: top k with a comparator that is wrong 10% of the time (then fewer calls, then a slow comparator), exploring a friend network through a restricted API with as few calls as possible.

Questions Mercor asks in this round 5

Top k with a deterministically noisy comparatorCodingYou must rank items through a comparison function cmp(a, b) that is wrong about 10% of the time, and consistently so: asking about the same pair again gives the same answer. Given…
Last asked Sep 2026
Can every car park with preferred spots and forward-only overflowCodingA one-way street has n spots numbered 0 to n - 1. Cars arrive in order; car i wants spot preferencesi, takes it if free, and otherwise drives forward to the next free spot. A car…
Last asked Sep 2026
Explore a friend graph through a remote API with few callsCodingYou cannot read a social graph directly; the only access is getfriends(userid), a remote call that returns a user's friends and costs a network round trip. Write code that…
Last asked Sep 2026
Exchange rate between two currencies through chained conversionsCodingYou get a list of rates from, to, rate, each meaning one unit of from is worth rate units of to. Given a source and a target currency, return the rate between them by chaining…
Last asked Sep 2026
Referral networkCodingImplement a referral network: users refer other users, and the network records who referred whom. Support adding referrals and answering questions about a user's referrals, such…
Last asked May 2026