eBay Interview Guide

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#1. Partition Equal Subset Sum

ArraysDynamic Programming

Determine if a given array of numbers can be divided into two subsets with equal sums. Essentially, can you split the array so both sides add up to the same value?

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Remove One Element to Make the Array Strictly Increasing

Determine if removing a single element from an array can make the remaining elements strictly increasing. You need to check if it's possible to obtain a strictly increasing sequence by deleting at most one element.

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#2. Remove One Element to Make the Array Strictly Increasing

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LRU Cache

Design a data structure that acts as a Least Recently Used (LRU) cache. Implement methods to get and put key-value pairs, evicting the least recently used entry when the cache is full.

Linked ListsDynamic Programming

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#3. LRU Cache

Linked ListsDynamic Programming

Design a data structure that acts as a Least Recently Used (LRU) cache. Implement methods to get and put key-value pairs, evicting the least recently used entry when the cache is full.

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Subtree of Another Tree

Determine if one binary tree is a subtree of another binary tree. That is, check if the structure and node values of the smaller tree exactly match a portion of the larger tree.

TreesRecursion

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#4. Subtree of Another Tree

This question is very likely to be asked in your eBay interview

Determine if one binary tree is a subtree of another binary tree. That is, check if the structure and node values of the smaller tree exactly match a portion of the larger tree.

TreesRecursion

Alternating Digit Sum

Calculate the alternating sum of digits in a given number. You'll add the first digit, subtract the second, add the third, and so on.

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#5. Alternating Digit Sum

Calculate the alternating sum of digits in a given number. You'll add the first digit, subtract the second, add the third, and so on.

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Design Skiplist

Implement a Skiplist data structure that supports efficient search, insertion, and deletion of elements. A Skiplist is a probabilistic data structure with multiple levels of linked lists.

Linked Lists

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#6. Design Skiplist

This question is very likely to be asked in your eBay interview

Implement a Skiplist data structure that supports efficient search, insertion, and deletion of elements. A Skiplist is a probabilistic data structure with multiple levels of linked lists.

Linked Lists

Minimize Maximum Pair Sum in Array

You're given an array of numbers. Pair them up to minimize the largest sum among all pairs.

ArraysTwo PointersGreedy Algorithms

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#7. Minimize Maximum Pair Sum in Array

ArraysTwo PointersGreedy Algorithms

You're given an array of numbers. Pair them up to minimize the largest sum among all pairs.

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Binary Gap

Find the longest sequence of consecutive zeros (the binary gap) between ones in the binary representation of a given positive integer.

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#8. Binary Gap

Find the longest sequence of consecutive zeros (the binary gap) between ones in the binary representation of a given positive integer.

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Minimum Window Subsequence

Find the shortest subsequence in a string S that contains all characters of another string T in the correct order. You need to find the minimum window in S that is a subsequence of T.

StringsDynamic ProgrammingTwo Pointers

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#9. Minimum Window Subsequence

StringsDynamic ProgrammingTwo Pointers

Find the shortest subsequence in a string S that contains all characters of another string T in the correct order. You need to find the minimum window in S that is a subsequence of T.

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Number of Islands

Given a grid representing land and water, count the number of distinct islands. An island is formed by connected land cells.

GraphsArrays

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#10. Number of Islands

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Given a grid representing land and water, count the number of distinct islands. An island is formed by connected land cells.

GraphsArrays

Spiral Matrix

Traverse a given matrix in a spiral pattern, returning all elements in the order you visit them. Essentially, walk around the matrix layer by layer, adding elements to a list.

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#11. Spiral Matrix

Traverse a given matrix in a spiral pattern, returning all elements in the order you visit them. Essentially, walk around the matrix layer by layer, adding elements to a list.

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Word Ladder

Transform one word into another, one letter at a time, using only words from a given dictionary. Find the shortest sequence of words to reach the target.

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#12. Word Ladder

Transform one word into another, one letter at a time, using only words from a given dictionary. Find the shortest sequence of words to reach the target.

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Open the Lock

You're given a lock with four dials, each 0-9. Find the minimum number of turns to open the lock to a target combination, avoiding a list of dead ends.

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#13. Open the Lock

You're given a lock with four dials, each 0-9. Find the minimum number of turns to open the lock to a target combination, avoiding a list of dead ends.

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Course Schedule

Determine if it is possible to finish all courses given prerequisites. Some courses must be taken before others; can you find a valid order?

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#14. Course Schedule

Determine if it is possible to finish all courses given prerequisites. Some courses must be taken before others; can you find a valid order?

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Word Search II

You are given a board of characters and a list of words. Find all the words from the list that can be formed by traversing adjacent cells on the board.

ArraysStringsRecursionGraphs

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#15. Word Search II

ArraysStringsRecursionGraphs

You are given a board of characters and a list of words. Find all the words from the list that can be formed by traversing adjacent cells on the board.

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Move Zeroes

Given an array, rearrange it so that all zeros are moved to the end while maintaining the relative order of the non-zero elements.

ArraysTwo Pointers

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#16. Move Zeroes

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Given an array, rearrange it so that all zeros are moved to the end while maintaining the relative order of the non-zero elements.

ArraysTwo Pointers

Binary Tree Zigzag Level Order Traversal

Traverse a binary tree level by level. Return the nodes in a list, alternating the order of nodes from left to right and right to left for each level.

Trees

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#17. Binary Tree Zigzag Level Order Traversal

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Traverse a binary tree level by level. Return the nodes in a list, alternating the order of nodes from left to right and right to left for each level.

Trees

Set Matrix Zeroes

Given a matrix, if any element is zero, set its entire row and column to zero. Do this in-place.

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#18. Set Matrix Zeroes

Given a matrix, if any element is zero, set its entire row and column to zero. Do this in-place.

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Course Schedule II

You're given a list of courses and their prerequisites. Determine a valid order in which you can take all the courses, respecting the dependencies. If it's impossible to finish all courses, indicate that.

GraphsDynamic Programming

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#19. Course Schedule II

GraphsDynamic Programming

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Valid Parentheses

Determine if a string containing parentheses is valid. A valid string has matching and properly nested opening and closing parentheses.

StringsStacks