Start Here
How this course works
What this lesson covers
This course is a sequence, not a topic list. Arrays and hashing come first because Two Sum needs a HashMap. Recursion comes before backtracking because backtracking is recursion that undoes its own moves. Dynamic programming comes after recursion because DP is recursion that stops repeating itself. Trees and graphs come last because by then every technique they need is already familiar. Work each day in the same order: watch the video, read the code and run it, then attempt the practice before moving on. The practice on every day is solvable with what you have already seen — if you find yourself needing something you have not learned, you have misread the problem, not run out of knowledge.
The code
The most common way to fail this course is to watch all 85 videos and write none of the code. Watching builds recognition; writing builds recall. The interview asks for recall.
Practice
Everything here can be solved with what you already know from this lesson and the ones before it. Nothing needs a technique from a later day.
- Print the largest value in {5, 2, 9, 1} using a single loop.
- Print the array backwards without creating a second array.
- Count how many values in the array are even.
Before you move on
If you can write the three practice programs without looking anything up, you are ready for Day 1.