How To Pseudocode
I’ve never been great at “pseudocoding”, but I have always understood that it’s an essential tool for programmers, for both newbies and experienced programmers. Pseudocode acts as a bridge between the initial concept of a program and its final code. It allows programmers to express the logic of their solutions in a structured format that is language agnostic, focusing solely on the thought process rather than syntax. Pseudocode is like a first draft.
Understanding Pseudocode
Pseudocode is tricky though. It’s hard to pin down because it doesn’t follow any strict syntax rules of programming languages. Instead, pseudocode uses a combination of natural language with high level keywords that look like real code. It’s common to structure pseudocode like an outline. Below is an example:
Initialize like_count to 0
IF user clicks on like_button
IF post is not already liked
Increment like_count
Display updated like_count
Mark post as liked
ELSE
Decrement like_count
Display updated like_count
Mark post as unliked
ENDIF
Even when we use keywords like IF, ELSE, and variable names like like_button, the above still reads like plain English, but it’s also pretty close on how real code would be structured.
Here’s a more conversational example that’s probably less “pseudocody”, but still, to me, valid pseudocode:
Start with like_count as 0.
If the user clicks on the like button:
If the post is not already liked:
Increase like_count by one.
Show the new like_count.
Set the post status to liked.
Otherwise:
Reduce like_count by one.
Show the new like_count.
Set the post status to unliked.
The important thing is that it clarifies what you need to do before you start typing the actual code.
Benefits of Pseudocode:
Clarity: It simplifies the expression of complex logic without getting bogged down by the syntax of a programming language.
Flexibility: It can be adapted to any programming language, making it a versatile tool in multi-language environments.
Debugging: By planning the logic before coding, you can identify potential issues early in the development process.
Collaboration: It helps in sharing ideas with others who may not know the specific syntax of a programming language you use.
How to Write Effective Pseudocode
Let’s use the extremely popular Two Sum(the new FizzBuzz) coding challenge. This problem is stated as follows on Leetcode:
Given an array of integers
nums
and an integertarget
, return indices of the two numbers such that they add up totarget
.You may assume that each input would have exactly one solution, and you may not use the same element twice.
Below is an example on how you can write the pseudocode for solving this problem the optimal way:
// Initialize an empty dictionary to store numbers and their indices
Create a dictionary/object called index_map
// Loop through each number in the list with its index
For each number and its index in the list:
// Calculate the complement by subtracting the current number from the target
Calculate complement as target minus current number
// Check if the complement is already in the index_map
If complement is in index_map:
// If found, return the indices of the current number and its complement
Return the index of complement from index_map and the current index
EndIf
// If not found, add the current number and its index to the index_map
Add current number and its index to index_map
EndFor
// If no such pair is found, indicate that no solution exists
Return "No valid pairs found"
Explanation:
Start with a clear problem statement: The pseudocode begins with a clear definition of the problem it aims to solve — finding two numbers that sum up to a given target.
Use simple language: The pseudocode uses simple language without specific programming syntax. Terms like “dictionary” and “complement” are used because they are generic enough to be understood in the context of programming.
Incorporate programming structure: It utilizes loops and conditional statements (if-else) to describe the logic flow. The use of a dictionary (or map) helps in explaining how to efficiently look up the required complement value.
Keep it consistent: The format is consistent with simple English descriptions and clear, step-by-step instructions.
Include comments: Each major step has a comment explaining its purpose, which helps clarify the intent of the code blocks.
Refine and iterate: This pseudocode can be refined or expanded based on peer feedback or specific requirements of the programming environment or language to be used.
This structured approach not only helps in understanding and implementing the solution but also makes the pseudocode accessible to others, aiding in collaborative environments.
Mastering the art of pseudocode is about learning to think computationally. It’s an invaluable skill that enhances clarity, improves problem-solving abilities, and fosters better communication when it comes to working with other programmers. By integrating pseudocode into your planning process, you can streamline the development of your projects. When working in teams it will give a roadmap from concept to code. Whether you’re a student or a seasoned professional, refining your pseudocode skills will pay dividends throughout your programming career. So get on it.