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Hi there! Today we will explore how to store lots of items in a single, organized list.
Imagine you have a collection of favorite video games. Instead of creating a new variable for every single game, you can use a list. A list is a single container that holds many items in a specific order.
Every item in a list has an index, which is like its street address. In coding, we start counting at zero! The first item is at index 0, the second is at index 1, and so on.
We can use nested loops to look through lists inside other lists. To design this, we break the big goal into smaller subproblems. First, we look at one row. Next, we look at each item in that row.
Let us design a program to search for a gold star in a 2D grid of boxes. We will use a software design process to solve this with nested loops.
- Identify the subproblems: We need to check each row one by one, and check each box inside that row.
- Create the outer loop: This loop starts at the first row (index 0) and goes to the last row.
- Create the inner loop: Inside the outer loop, write a second loop to check each box in the current row.
- Add the check: If the box contains 'gold star', print the row and box index.
- Run the program: The outer loop selects Row 0. The inner loop checks Box 0, then Box 1. It finds the star!
