What is Interview Forge?

Interview Forge helps you practice mock interviews, follow study plans, track career goals, review learning analytics, and prepare across 36 pages.

Permutations at Uber — Interview Guide

How to approach Permutations in a Uber interview: the optimal approach, what Uber interviewers look for, and company-specific tips.

Updated 2026-09MediumBacktracking

The problem at Uber

Given a list of distinct integers, return all possible permutations.

Uber uses this problem to assess real-time systems and marketplaces. Expect Uber-specific follow-ups that tie the solution back to production reasoning and the company's engineering bar.

Key concepts

Swap-based backtracking produces permutations in place with O(n) extra space for the recursion.
Pick-based backtracking (used/unused set) is more intuitive but uses more memory.
For duplicates, sort and skip a duplicate when the identical previous element was not used in this branch.

Approach

def permute(nums):
    res = []
    def bt(first):
        if first == len(nums):
            res.append(nums[:]); return
        for i in range(first, len(nums)):
            nums[first], nums[i] = nums[i], nums[first]
            bt(first + 1)
            nums[first], nums[i] = nums[i], nums[first]
    bt(0)
    return res

What Uber looks for

Real-time and distributed systems intuition.
Geospatial and concurrency reasoning.
Pragmatic, production-minded engineering.
Ownership of features end-to-end.

Unlock the full guide

Premium members get every DSA, system design, company and role interview guide — plus AI practice, mock interviews, and analytics.

Unlock with Premium