You get to a gorge. There are hundreds of piles of 20 different types of hover-blocks that will form into a bridge as try to walk across. The hover-blocks support each other pairs that build from each end of the bridge simultaneously (except for the middle, which can have one lone block). So in a stack of CBABA, as you step forwards the span will be:
A---A
AB-BA
ABCBA.

But the bridge will collapse when you’re crossing it if it ever gets to the the point where it can’t be perfectly symmetric (palindromic in this case). DCABAB would go:
A----A
AB--BA
ABCDBA (collapse, because the C and D can’t support each other).

How do you configure your bot to examine the piles and find one that will work?

Main concept: Permutations, Big O introduction

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code.org (https://code.org) has great resources for students and teachers. It also includes an extensive curriculum mapped to K-12 curriculum standards (https://curriculum.code.org/csf-19/standards/).

If you’re looking for programming challenges, check out the Advent of Code, which is run by Eric Wastl, who consulted extensively on Think Like a Coder and inspired quite a few of the puzzles. The Advent of Code is a yearly event that takes place in December and involves 25 coding challenges linked together by an overarching plot. It’s also available throughout the rest of the year, and the challenges it features are a great way to stretch your coding and problem-solving skills once you have basic proficiency with a programming language.

FreeCodeCamp (https://www.freecodecamp.org) has thousands of coding lessons and programming challenges, and you can even get certified for a few different skills.

University of Michigan's Python for Everybody Specialization on Coursera (https://www.coursera.org/specializations/python) is a beginner-level intro to software development using python that focuses on interacting with data.

Microsoft has a 44 video series called Python for Beginners. In their words, “Even though we won’t cover everything there is to know about Python in the course, we want to make sure we give you the foundation on programming in Python, starting from common everyday code and scenarios. At the end of the course, you’ll be able to go and learn on your own, for example with docs, tutorials, or books.”

If you’re trying to decide what programming language to learn, a flowchart like this one may be a helpful starting point.

Books
Girls Who Code: Learn to Code and Change the World by Reshma Saujani, founder of Girls Who Code, is an excellent introduction for programmers just getting started.

For more experienced programmers, Cracking the Coding Interview is a great resource for problem solving with a variety of different techniques, as well as preparing for coding interviews (as the title suggests). Some of the puzzles featured in Think Like a Coder were inspired by this book.

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