| Day 0: Hello, World. |
Practice reading from stdin and printing to stdout. |
C Python |
Easy |
| Day 1: Data Types |
Get started with data types. |
C++ Python |
Easy |
| Day 2: Operators |
Start using arithmetic operators. |
C++ Python |
Easy |
| Day 3: Intro to Conditional Statements |
Get started with conditional statements. |
C++ |
Easy |
| Day 4: Class vs. Instance |
Learn the difference between class variables and instance variables. |
Python |
Easy |
| Day 5: Loops |
Let’s talk about loops. |
Python |
Easy |
| Day 6: Let’s Review |
Characters and Strings |
C++ Python |
Easy |
| Day 7: Arrays |
Getting started with Arrays. |
C++ Python |
Easy |
| Day 8: Dictionaries and Maps |
Mapping Keys to Values using a Map or Dictionary. |
Python |
Easy |
| Day 9: Recursion |
Use recursion to compute the factorial of number. |
Python |
Easy |
| Day 10: Binary Numbers |
Find the maximum number of consecutive 1’s in the base-2 representation of a base-10 number. |
C++ Python |
Easy |
| Day 11: 2D Arrays |
Find the maximum sum of any hourglass in a 2D-Array. |
C++ Python |
Easy |
| Day 12: Inheritance |
Learn about inheritance. |
C++ |
Easy |
| Day 13: Abstract Classes |
Build on what you’ve already learned about Inheritance with this Abstract Classes challenge |
C++ Python |
Easy |
| Day 14: Scope |
Learn about the scope of an identifier. |
C++ Python |
Easy |
| Day 15: Linked List |
Complete the body of a function that adds a new node to the tail of a Linked List. |
C++ Python |
Easy |
| Day 16: Exceptions - String to Integer |
Can you determine if a string can be converted to an integer? |
C++ Python |
Easy |
| Day 17: More Exceptions |
Throw an exception when user sends wrong parameters to a method. |
C++ |
Easy |
| Day 18: Queues and Stacks |
Use stacks and queues to determine if a string is a palindrome. |
Python |
Easy |
| Day 19: Interfaces |
Welcome to Day 19! Learn about interfaces in this challenge! |
C++ |
Easy |
| Day 20: Sorting |
Find the minimum number of conditional checks taking place in Bubble Sort |
C++ |
Easy |
| Day 21: Generics |
Welcome to Day 21! Review generics in this challenge! |
C++ |
Easy |
| Day 22: Binary Search Trees |
Given a binary tree, print its height. |
Python |
Easy |
| Day 23: BST Level-Order Traversal |
Implement a breadth-first search! |
C++ Python |
Easy |
| Day 24: More Linked Lists |
Welcome to Day 24! Review everything we’ve learned so far and learn more about Linked Lists in this challenge. |
C++ |
Easy |
| Day 25: Running Time and Complexity |
Determine if a number is prime in optimal time! |
C++ Python |
Medium |
| Day 26: Nested Logic |
Test your understanding of layered logic by calculating a library fine! |
C++ |
Easy |
| Day 27: Testing |
Welcome to Day 27! Review testing in this challenge! |
Python |
Easy |
| Day 28: RegEx, Patterns, and Intro to Databases |
Review Pattern documentation and start using Regular Expressions |
Python |
Medium |
| Day 29: Bitwise AND |
Apply everything we’ve learned in this bitwise AND challenge. |
C++ |
Medium |