Written by: Brian Jenney | Data Structures and Algorithms, Interview Preparation

We’re going to go through a bulletproof study plan to get you prepared for 90% of interviews that require data structures and algorithms.

Besides passing interviews, the benefits of learning data structures and algorithms are:

• Increased problem-solving ability
• Exposure to fundamental computer science concepts
• Confidence

Unfortunately, most people do random LeetCode problems expecting to come out on the other end interview-ready. That’s like going to the gym with no plan, throwing random weights around, and expecting to get buff.

Study concepts, not problems.

I spent over $10k learning data structures and algos over the years. I’m going to break down exactly how I went from not knowing Big O to making it to the final rounds at companies like Google and Facebook and landing offers from high-growth startups.

Here’s what you should study, in order:

Big O Notation

Estimated Study Time

1 day

Concepts:

• Space vs time complexity
• Linear time
• Logarithmic time
• Factorial time
• Constant time
• Exponential time

How to Study:

• Read: FreeCodeCamp Big O OR Digital Ocean Big O
• Write the Big O next to every problem you solve

Sorting and Searching

Estimated Study Time

1 week

Concepts:

• Merge sort
• Quick sort
• Bubble sort (and why you would never use this!)
• Hoare vs Lomuto partitioning (BONUS points)

How to study:

• Create each sorting and searching algo from scratch

Stacks and Queues

Estimated Study Time

1 day

Concepts:

• Stacks
• Queues
• LIFO
• FIFO

How to study:

• Create a stack and queue from scratch

Heaps

Estimated Study Time

2 days

Concepts:

• Max heap
• Min heap
• Priority queue

How to study:

• Create a max and min heap from scratch

Trees and Tries

Estimated Study Time

1 week

Concepts:

• Binary trees and Binary search trees (there’s a difference)
• Depth-first search
• Breadth-first search
• What the heck is a trie?

How to study:

• Create a binary tree, binary search tree, and a trie from scratch

Recursion

Estimated Study Time

1 week

Concepts:

• Recursion vs backtracking
• Call stack
• Stack overflows (the concept, not the site)

How to study:

• Solve problems that require finding combinations and permutations

Linked Lists

Estimated Study Time

1 week

Concepts:

• Singly linked list
• Doubly linked list

How to study:

• Create an LRU cache leveraging a LL

Graphs

Estimated Study Time

1 week

Concepts:

• Directed vs undirected graphs
• Adjacency list
• Adjacency matrix

How to study:

• Create graph structures using adjacency and matrix representations with DFS and BFS methods

Dynamic Programming

Estimated Study Time

1 week

Concepts:

• Dynamic programming vs recursion
• Top-down vs bottom-up memoization

How to study:

• Solve Fibonacci using DP

Miscellaneous but Important!

Estimated Study Time

2 weeks

Concepts:

• 2 pointers
• Frequency counters
• Sliding window

How to study:

• Look up + Leetcode and solve at least 2 problems under each concept

Conclusion

Holy moly, that’s a lot to study… or is it? I gave fairly aggressive estimates for how long I would expect you to take to study the bare minimum.

It’s enough to get a solid understanding of the most common concepts and can be done over a couple of months.

For most interviews, that’s really all you need.

If you want to become a software developer and build complex stuff that does not suck. Apply here.