This post covers Chapter 6 of Grokking Algorithms, which introduces the graph data structure and the breadth-first search algorithm. Shortest Path Imagine you’re going on vacation and you need someone to watch your pet gecko while you’re gone. His name is Gordon and he’s very picky about who takes care of him. His preference would be to have one of your friends watch him. But if none of them…

This post covers Chapter 5 of Grokking Algorithms, which introduces hash tables. Hash Table A hash table is a data structure that provides quick access to key-value pairs. It does this by using a hash function to determine where in memory a particular value is stored. Since each key in a hash table must be unique, a key can predictably be translated into a memory offset. Hash Function This…

This post covers Chapter 4 from Grokking Algorithms, which introduces the Divide and Conquer approach as a lead-in to the Quicksort algorithm. Divide and Conquer When I was ten years old, I participated in a weeklong camp program as part of my fifth grade class. The participants were divided into groups, with each group assigned a guide. One night, our guide told a fable about a village in…

This post covers Chapter 3 from Grokking Algorithms, which focuses on recursion. Recursion Recursion is an unique concept. It’s similar to looping in that you iterate through a collection of items. It’s different in that each iteration depends on the result of all subsequent iterations. A good analogy to recursion is a set of Russian nesting dolls. You start with all of the dolls unnested in a…

This post covers the algorithm from Chapter 2, selection sort. Imagine you have a row of numbered billiard balls, arranged in a random order and you want to sort them in order from smallest to largest. You start by picking up the first ball and then move down the line, comparing each of the balls in the row to the one in your hand. As soon as you find one with a number smaller than the one…

I’m awful at algorithms. There, I said it. I could blame my college algorithms professor or the fact that I’ve never had to use fancy algorithms at work. But anytime I’m on the market for a new job, I’m confronted with the inevitable HackerRank or LeetCode challenge and I stumble, remembering my biggest weakness as a software engineer. Now that I’m happy with my current job, I figure it’s a…