Google L4-L6 Prep
16 Topics

Learning to pass
the interview

Structured prep covering the data structures and algorithms big-tech interviews expect. Interactive visualizations, a Python playground, AI-powered feedback, and progress tracking.

Google Interview Readiness
0Just Starting
Start practicing to build your score
Try it now - no signupTwo Sum · easy

Solve a real Google interview question, right here

Given an array of integers `nums` and an integer `target`, return the indices of the two numbers that add up to `target`. Each input has exactly one solution. You may not use the same element twice.

Time:O(n)
Space:O(n)
Real Python, real tests - it all runs in your browser.
solution.py
⌘↵ run
Loading...
OUTPUT

Run your code to see output

Not sure where to start?
Follow the skill tree - learn concepts in the right order with prerequisites mapped out.
View Learning Path
0/16
Topics Mastered
0
Challenges Solved
0
Active This Week

Data Structures

8 topics
0% avg mastery
4071229314LRtwo-pointer
Beginner

Arrays & Strings

avg O(n)space O(1)
Mastery0%
0/3 challenges
head3719nullsingly linked
Easy

Linked Lists

avg O(n)space O(1)
Mastery0%
0/2 challenges
9527push/popLIFO
Easy

Stacks & Queues

avg O(1)space O(n)
Mastery0%
0/2 challenges
"key"hash%501234chaining
Easy

Hash Tables

avg O(1)space O(n)
Mastery0%
0/2 challenges
8412261014BSTleft < parent < right
Intermediate

Binary Trees

avg O(log n)space O(h)
Mastery0%
0/2 challenges
ABCDEdirected + undirected edges
Advanced

Graphs

avg O(V + E)space O(V + E)
Mastery0%
0/2 challenges
1327456bubble upmin-heap
Intermediate

Heaps / Priority Queues

avg O(log n)space O(n)
Mastery0%
0/1 challenges
catrpcatrpcatcarcap
Advanced

Tries

avg O(m)space O(n * m)
Mastery0%
0/1 challenges

Algorithms

6 topics
0% avg mastery
✓✓swap?comparison sort
Easy

Sorting

avg O(n log n)space O(log n)
Mastery0%
0/1 challenges
1031527394115LRmidO(log n) search
Easy

Binary Search

avg O(log n)space O(1)
Mastery0%
0/2 challenges
f(n)f(n-1)f(n-1)f(n-2)f(n-2)f(n-2)call tree / backtracking
Intermediate

Recursion & Backtracking

avg O(2^n)space O(n)
Mastery0%
0/1 challenges
dp[i][j]✓bottom-up memoization
Expert

Dynamic Programming

avg O(n^2)space O(n)
Mastery0%
0/2 challenges
12345queue: [3, 4, 5]BFS/DFS traversal
Intermediate

BFS & DFS

avg O(V + E)space O(V)
Mastery0%
0/1 challenges
pick locally optimal25✓10✓51coin change greedy
Intermediate

Greedy Algorithms

avg O(n log n)space O(1)
Mastery0%
0/1 challenges

Concepts

2 topics
0% avg mastery
n (input size)timeO(n²)O(n)O(log n)O(1)
Beginner

Big-O Notation

avg N/Aspace N/A
Mastery0%
0/1 challenges
ClientLoadBalancerServerServerDBCacheclient - LB - servers - DB
Advanced

System Design Basics

avg O(1)space O(n)
Mastery0%
0/1 challenges