eBay Coding Interview Questions

Partition Equal Subset Sum

Given an integer array nums, return true if you can partition the array into two subsets such that the sum of the elements in both subsets is equal or false oth...

LRU Cache

Design a data structure that follows the constraints of a Least Recently Used (LRU) cache.

Subtree of Another Tree

Given the roots of two binary trees root and subRoot, return true if there is a subtree of root with the same structure and node values of subRoot and false oth...

Remove One Element to Make the Array Strictly Increasing

Given a 0-indexed integer array nums, return true if it can be made strictly increasing after removing exactly one element, or false otherwise. If the array is...

Minimize Maximum Pair Sum in Array

The pair sum of a pair (a,b) is equal to a + b. The maximum pair sum is the largest pair sum in a list of pairs.

Binary Gap

Given a positive integer n, find and return the longest distance between any two adjacent 1's in the binary representation of n. If there are no two adjacent 1'...

Design Skiplist

Design a Skiplist without using any built-in libraries.

Alternating Digit Sum

You are given a positive integer n. Each digit of n has a sign according to the following rules:

Number of Islands

Given an m x n 2D binary grid grid which represents a map of '1's (land) and '0's (water), return the number of islands.

Word Ladder

A transformation sequence from word beginWord to word endWord using a dictionary wordList is a sequence of words beginWord -> s1 -> s2 -> ... -> sk such that:

Open the Lock

You have a lock in front of you with 4 circular wheels. Each wheel has 10 slots: '0', '1', '2', '3', '4', '5', '6', '7', '8', '9'. The wheels can rotate freely...

Move Zeroes

Given an integer array nums, move all 0's to the end of it while maintaining the relative order of the non-zero elements.

Group Anagrams

Given an array of strings strs, group the anagrams together. You can return the answer in any order.

Spiral Matrix

Given an m x n matrix, return all elements of the matrix in spiral order.

Word Search II

Given an m x n board of characters and a list of strings words, return all words on the board.

Binary Tree Zigzag Level Order Traversal

Given the root of a binary tree, return the zigzag level order traversal of its nodes' values. (i.e., from left to right, then right to left for the next level...

Reconstruct Itinerary

You are given a list of airline tickets where tickets[i] = [fromi, toi] represent the departure and the arrival airports of one flight. Reconstruct the itinerar...

Longest Continuous Subarray With Absolute Diff Less Than or Equal to Limit

Given an array of integers nums and an integer limit, return the size of the longest non-empty subarray such that the absolute difference between any two elemen...

Valid Parentheses

Given a string s containing just the characters '(', ')', '{', '}', '[' and ']', determine if the input string is valid.

Kth Largest Element in an Array

Given an integer array nums and an integer k, return the kth largest element in the array.

Course Schedule II

There are a total of numCourses courses you have to take, labeled from 0 to numCourses - 1. You are given an array prerequisites where prerequisites[i] = [ai, b...

Course Schedule

There are a total of numCourses courses you have to take, labeled from 0 to numCourses - 1. You are given an array prerequisites where prerequisites[i] = [ai, b...

Set Matrix Zeroes

Given an m x n integer matrix matrix, if an element is 0, set its entire row and column to 0's.

Longest ZigZag Path in a Binary Tree

You are given the root of a binary tree.

Rotting Oranges

You are given an m x n grid where each cell can have one of three values:

Two Sum

Given an array of integers nums and an integer target, return the indices of the two numbers that add up to target.

Longest Substring Without Repeating Characters

Given a string s, find the length of the longest substring without duplicate characters.

Pow(x, n)

Implement pow(x, n), which calculates x raised to the power n (i.e., xn).

Search in Rotated Sorted Array

There is an integer array nums sorted in ascending order (with distinct values).

Design a Stack With Increment Operation

Design a stack that supports increment operations on its elements.

Binary Search Tree to Greater Sum Tree

Given the root of a Binary Search Tree (BST), convert it to a Greater Tree such that every key of the original BST is changed to the original key plus the sum o...

Best Time to Buy and Sell Stock II

You are given an integer array prices where prices[i] is the price of a given stock on the ith day.

Decode String

Given an encoded string, return its decoded string.

Concatenated Words

Given an array of strings words (without duplicates), return all the concatenated words in the given list of words.

Generate Parentheses

Given n pairs of parentheses, write a function to generate all combinations of well-formed parentheses.

Two Sum II - Input Array Is Sorted

Given a 1-indexed array of integers numbers that is already sorted in non-decreasing order, find two numbers such that they add up to a specific target number....

Matchsticks to Square

You are given an integer array matchsticks where matchsticks[i] is the length of the ith matchstick. You want to use all the matchsticks to make one square. You...

Nearest Exit from Entrance in Maze

You are given an m x n matrix maze (0-indexed) with empty cells (represented as '.') and walls (represented as '+'). You are also given the entrance of the maze...

Maximum Tastiness of Candy Basket

You are given an array of positive integers price where price[i] denotes the price of the ith candy and a positive integer k.

Roman to Integer

Roman numerals are represented by seven different symbols: I, V, X, L, C, D and M.

Rotate Array

Given an integer array nums, rotate the array to the right by k steps, where k is non-negative.

Best Time to Buy and Sell Stock

You are given an array prices where prices[i] is the price of a given stock on the ith day.

Maximum Subarray

Given an integer array nums, find the subarray with the largest sum, and return its sum.

Longest Palindromic Substring

Given a string s, return the longest palindromic substring in s.

Find Peak Element

A peak element is an element that is strictly greater than its neighbors.

Longest Common Prefix

Write a function to find the longest common prefix string amongst an array of strings.

Shortest Palindrome

You are given a string s. You can convert s to a palindrome by adding characters in front of it.

Majority Element

Given an array nums of size n, return the majority element.

Product of Array Except Self

Given an integer array nums, return an array answer such that answer[i] is equal to the product of all the elements of nums except nums[i].

Koko Eating Bananas

Koko loves to eat bananas. There are n piles of bananas, the ith pile has piles[i] bananas. The guards have gone and will come back in h hours.

Integer to Roman

Seven different symbols represent Roman numerals with the following values:

Median of Two Sorted Arrays

Given two sorted arrays nums1 and nums2 of size m and n respectively, return the median of the two sorted arrays.

Permutations

Given an array nums of distinct integers, return all the possible permutations. You can return the answer in any order.

Sort Colors

Given an array nums with n objects colored red, white, or blue, sort them in-place so that objects of the same color are adjacent, with the colors in the order...

First Missing Positive

Given an unsorted integer array nums. Return the smallest positive integer that is not present in nums.

Merge k Sorted Lists

You are given an array of k linked-lists lists, each linked-list is sorted in ascending order.

Longest Valid Parentheses

Given a string containing just the characters '(' and ')', return the length of the longest valid (well-formed) parentheses substring.

Validate Binary Search Tree

Given the root of a binary tree, determine if it is a valid binary search tree (BST).

Find Pivot Index

Given an array of integers nums, calculate the pivot index of this array.

Maximal Square

Given an m x n binary matrix filled with 0's and 1's, find the largest square containing only 1's and return its area.

Time Based Key-Value Store

Design a time-based key-value data structure that can store multiple values for the same key at different time stamps and retrieve the key's value at a certain...

Minimum Path Sum

Given a m x n grid filled with non-negative numbers, find a path from top left to bottom right, which minimizes the sum of all numbers along its path.

Top K Frequent Elements

Given an integer array nums and an integer k, return the k most frequent elements. You may return the answer in any order.

Rank Teams by Votes

In a special ranking system, each voter gives a rank from highest to lowest to all teams participating in the competition.

Valid Palindrome II

Given a string s, return true if the s can be palindrome after deleting at most one character from it.

Integer to English Words

Convert a non-negative integer num to its English words representation.

Isomorphic Strings

Given two strings s and t, determine if they are isomorphic.

Word Break

Given a string s and a dictionary of strings wordDict, return true if s can be segmented into a space-separated sequence of one or more dictionary words.

Find Minimum in Rotated Sorted Array

Suppose an array of length n sorted in ascending order is rotated between 1 and n times. For example, the array nums = [0,1,2,4,5,6,7] might become:

Reorganize String

Given a string s, rearrange the characters of s so that any two adjacent characters are not the same.

Vertical Order Traversal of a Binary Tree

Given the root of a binary tree, calculate the vertical order traversal of the binary tree.

Binary Tree Cameras

You are given the root of a binary tree. We install cameras on the tree nodes where each camera at a node can monitor its parent, itself, and its immediate chil...

Copy List with Random Pointer

A linked list of length n is given such that each node contains an additional random pointer, which could point to any node in the list, or null.