Back to Open Book Shelf

Top-Down vs Bottom-Up

We've seen two distinct ways to approach a dynammic programming-based solution. Ultimately, you might wonder which approach to take: the top-down (recursive) approach or the bottom-up (iterative) approach.

Choosing Your Approach

There isn't a definitive answer to this question, as it often comes down to personal preference. Typically, students find the iterative approach easier to understand in the beginning. As they become more comfortable with dynamic programming, they tend to develop a preference for one approach over the other. It's rare to find students who feel equally confident with both techniques, and that's completely fine and expected.

It's also possible that you'll find one approach easier than the other based on the type of problem. If one way feels more intuitive, go ahead and use it.

You don't have to be proficient in solving these problems both ways. Choose the approach you find easiest to understand and focus on mastering that one.

Hi! I'm LSBot. I'm here to help you understand this chapter content with fast , focused answers. Any code from the editor will be automatically included with your question.

Ask me about concepts, examples, or anything you'd like clarified from this chapter. I can explain complex topics, provide examples, or help connect ideas.

Switch to Deep Dive mode if you want comprehensive answers across the entire curriculum. Responses may take longer, but I'll draw on the entire Launch School curriculum to give you a fuller picture.

Want to know more? Refer to the LSBot User Guide .

Deep Dive

GitHub Mode

GitHub Repository Submission

When using GitHub mode, paste your repository URL below and click Save URL to store it. The saved URL will be automatically included with every message you send until you choose to clear it. Learn more

GitHub Repository URL

Saved GitHub URL

Your GitHub repository URL is saved. LSBot will automatically fetch your latest code from this repository for each message. To change the URL, clear it first and save a new one.

Output

No output yet. Click "Run Code" to execute your code.

Normal Markdown & GFM

Github Flavored Markdown

**bold**

~~~~strike through~~~~

`single line of code`

Supports Emoji

Code Blocks

You can write code blocks using three backticks (```) followed by the language you want to show. For instance, if you wanted to write a Ruby code block you would write:

```ruby
class Foo
end
```

class Foo
end

You can also leave out the language identifier, doing this will make it so your code isn't highlighted at all, and all text will be white with no coloring.

```
class Bar
end
```

class Bar
end

Highlighting

You may highlight lines within your code blocks. This is a different type of highlighting, and isn't related to how the code within your code block may be colored depending on the language identifier used.
To highlight one or more lines of code, add # highlight on a separate line just before the first line you wish to highlight. To end highlighting, add # endhighlight on a separate line immediately after the last line you wish to highlight.

```ruby
def say_hello_world
# highlight
  puts 'Hello World!!!'
# endhighlight
end
```

def say_hello_world
# highlight
  puts 'Hello World!!!'
# endhighlight
end