Interview questions

Max Consecutive Ones III

Find the maximum length of a contiguous subarray that can be made all 1s by flipping at most k zeros — equivalently, find the longest…

Companies: Amazon, D. E. Shaw, LinkedIn, Meta

Array · Binary Search · Prefix Sum · Sliding Window

Last reported Sep 2026

Product of Array Except Self

For each index in an integer array, compute the product of all other elements without using division and in O(n) time — typically done by…

Companies: Amazon, Asana, Meta, Snap

Array · Prefix Sum

Last reported Sep 2026

Random Pick with Weight

Given an array of positive weights, implement pickIndex() to return index i with probability w[i]/sum(w); the typical approach preprocessing prefix sums and using a random…

Companies: Amazon, Apple, Goldman Sachs, Meta +4

Array · Binary Search · Math · Prefix Sum

Last reported Jun 2026

Subarray Sum Equals K

Count the number of contiguous, non-empty subarrays whose elements sum to k. Because nums can include negatives (so two-pointer sliding window doesn't work), use cumulative…

Companies: Amazon, Apple, Bloomberg, Google +3

Array · Hash Table · Prefix Sum

Last reported Mar 2026

Split Array Largest Sum

Split the array into k non-empty contiguous subarrays so that the maximum subarray sum is as small as possible, and return that minimized largest sum…

Companies: Amazon, Google, Microsoft, Pinterest +2

Array · Binary Search · Dynamic Programming · Greedy

Last reported Feb 2026

Minimum Size Subarray Sum

Find the length of the shortest contiguous subarray of positive integers whose sum is at least a given target (return 0 if none exists). This…

Companies: Bloomberg, Meta, Toast

Array · Binary Search · Prefix Sum · Sliding Window

Last reported Aug 2025

Shortest Subarray with Sum at Least K

Find the length of the shortest contiguous subarray whose sum is at least k, or return -1 if none exists. Because nums can contain negative…

Companies: Meta

Array · Binary Search · Heap (Priority Queue) · Monotonic Queue

Last reported Jan 2025

Contiguous Array

Find the maximum length of a contiguous subarray in a binary array that contains an equal number of 0s and 1s. This is solved by…

Companies: Cisco

Array · Hash Table · Prefix Sum

Count Non Decreasing Arrays With Given Digit Sums

Companies: Microsoft

Array · Dynamic Programming · Prefix Sum

Count Number of Nice Subarrays

Count the number of contiguous subarrays that contain exactly k odd numbers in an integer array. The core challenge is to do this in linear…

Companies: TikTok

Array · Hash Table · Math · Prefix Sum

Minimum Operations to Reduce X to Zero

Remove elements from either end to make the sum of removed elements equal x; equivalently, find the longest contiguous subarray whose sum equals total(nums) -…

Companies: Bloomberg

Array · Binary Search · Hash Table · Prefix Sum

Number of Flowers in Full Bloom

Given a list of closed time intervals for when each flower is in full bloom and query times for people arriving, return for each person…

Companies: Roblox

Array · Binary Search · Hash Table · Ordered Set

Number of Wonderful Substrings

Count the number of non-empty substrings (in a string of letters 'a'–'j') whose character counts have at most one odd frequency. Core idea: track a…

Companies: Uber

Bit Manipulation · Hash Table · Prefix Sum · String

Removing Minimum Number of Magic Beans

Given an array of positive integers (bag counts), remove beans (only deletions allowed) so that every non-empty bag has the same count, minimizing total beans…

Companies: D. E. Shaw

Array · Enumeration · Greedy · Prefix Sum

Subarray Sums Divisible by K

Count the number of contiguous subarrays whose sum is divisible by k; this reduces to counting pairs of prefix sums with the same remainder modulo…

Companies: TikTok

Array · Hash Table · Prefix Sum