Coding interview questions

Google Coding Interview Questions (DSA)

The 50 DSA problems Google has asked most in the last six months, most-asked first. 50 of them have a full breakdown with diagrams and code. Tick them off as you go.

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50problems
50full breakdowns
41topics

By difficulty: Easy (26) · Medium (20) · Hard (4)

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Topics

1.Two Sum
Full breakdownArrayHash Table
Easy+10▶ Mock
9.Palindrome Number
Full breakdownMath
Easy▶ Mock
4.Median of Two Sorted Arrays
Full breakdownArrayBinary SearchDivide and Conquer
Hard+5▶ Mock
3.Longest Substring Without Repeating Characters
Full breakdownHash TableStringSliding Window
Medium+13▶ Mock
15.3Sum
Full breakdownArrayTwo PointersSorting
Medium+5▶ Mock
2.Add Two Numbers
Full breakdownLinked ListMathRecursion
Medium+3▶ Mock
121.Best Time to Buy and Sell Stock
Full breakdownArrayDynamic Programming
Easy+10▶ Mock
13.Roman to Integer
Full breakdownHash TableMathString
Easy+1▶ Mock
1929.Concatenation of Array
Full breakdownArraySimulation
Easy▶ Mock
128.Longest Consecutive Sequence
Full breakdownArrayHash TableUnion-Find
Medium+3▶ Mock
5.Longest Palindromic Substring
Full breakdownTwo PointersStringDynamic Programming
Medium+8▶ Mock
88.Merge Sorted Array
Full breakdownArrayTwo PointersSorting
Easy+1▶ Mock
26.Remove Duplicates from Sorted Array
Full breakdownArrayTwo Pointers
Easy+1▶ Mock
Recyclable and Low Fat Products
Full breakdownDatabase
Easy▶ Mock
33.Search in Rotated Sorted Array
Full breakdownArrayBinary Search
Medium+5▶ Mock
7.Reverse Integer
Full breakdownMath
Medium▶ Mock
410.Split Array Largest Sum
Full breakdownArrayBinary SearchDynamic Programming
Hard▶ Mock
125.Valid Palindrome
Full breakdownTwo PointersString
Easy▶ Mock
169.Majority Element
Full breakdownArrayHash TableDivide and Conquer
Easy▶ Mock
Valid Anagram
Full breakdownHash TableStringSorting
Easy▶ Mock
49.Group Anagrams
Full breakdownArrayHash TableString
Medium+9▶ Mock
14.Longest Common Prefix
Full breakdownArrayStringTrie
Easy+1▶ Mock
560.Subarray Sum Equals K
Full breakdownArrayHash TablePrefix Sum
Medium+2▶ Mock
51.N-Queens
Full breakdownArrayBacktrackingAlgorithm X
Hard▶ Mock
22.Generate Parentheses
Full breakdownStringDynamic ProgrammingBacktracking
Medium+1▶ Mock
322.Coin Change
Full breakdownArrayDynamic ProgrammingBreadth-First Search
Medium+4▶ Mock
42.Trapping Rain Water
Full breakdownArrayTwo PointersDynamic Programming
Hard+6▶ Mock
11.Container With Most Water
Full breakdownArrayTwo PointersGreedy
Medium+6▶ Mock
35.Search Insert Position
Full breakdownArrayBinary Search
Easy▶ Mock
17.Letter Combinations of a Phone Number
Full breakdownHash TableStringBacktracking
Medium+1▶ Mock
70.Climbing Stairs
Full breakdownMathDynamic ProgrammingMemoization
Easy+4▶ Mock
Missing Number
Full breakdownArrayHash TableMath
Easy▶ Mock
Employees Earning More Than Their Managers
Full breakdownDatabase
Easy▶ Mock
20.Valid Parentheses
Full breakdownStringStackBracket Sequences
Easy+3▶ Mock
69.Sqrt(x)
Full breakdownMathBinary SearchNewton's Method
Easy▶ Mock
16.3Sum Closest
Full breakdownArrayTwo PointersSorting
Medium▶ Mock
Combine Two Tables
Full breakdownDatabase
Easy▶ Mock
219.Contains Duplicate II
Full breakdownArrayHash TableSliding Window
Easy▶ Mock
189.Rotate Array
Full breakdownArrayMathTwo Pointers
Medium+1▶ Mock
94.Binary Tree Inorder Traversal
Full breakdownStackTreeDepth-First Search
Easy▶ Mock
206.Reverse Linked List
Full breakdownLinked ListRecursion
Easy+4▶ Mock
217.Contains Duplicate
Full breakdownArrayHash TableSorting
Easy▶ Mock
198.House Robber
Full breakdownArrayDynamic Programming
Medium+1▶ Mock
45.Jump Game II
Full breakdownArrayDynamic ProgrammingGreedy
Medium▶ Mock
Happy Number
Full breakdownHash TableMathTwo Pointers
Easy+1▶ Mock
238.Product of Array Except Self
Full breakdownArrayPrefix Sum
Medium+5▶ Mock
912.Sort an Array
Full breakdownArrayDivide and ConquerSorting
Medium▶ Mock
167.Two Sum II - Input Array Is Sorted
Full breakdownArrayTwo PointersBinary Search
Medium▶ Mock
1752.Check if Array Is Sorted and Rotated
Full breakdownArray
Easy▶ Mock
66.Plus One
Full breakdownArrayMath
Easy▶ Mock

Frequently Asked Questions

What questions does Google ask in coding interviews?

Google coding interviews focus on Algorithm X, Array, Backtracking, Binary Search, and other data structure problems. We compiled 50 questions from real Google interviews. The most common topics are Algorithm X, Array, Backtracking, Binary Search, Binary Tree. Filter by topic to see what comes up most often.

How many Google coding interview questions are there?

InterviewSkool has 50 Google coding interview questions: 26 Easy, 20 Medium, and 4 Hard. Most Google interviews focus on Medium-difficulty problems, so prioritize those in your prep.

How should I prepare for Google coding interviews?

Start with Medium difficulty problems. Group by topic (Array, Tree, DP) to build pattern recognition. Aim to solve 30 to 40 problems before your interview. Then practice under pressure with a mock interview.

Are Google coding interview questions free?

Yes. All 50 Google coding interview questions are free to browse with no sign-up required. You can filter by difficulty and topic tags. Start a mock interview with a free credit to practice under real pressure.

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