Sum of Two Numbers - JavaScript Solution with O(1) Time Complexity

In this lesson we will introduce you to how challenges work and how to make the most out of them. Let's check your first coding challenge:

Sum of Two Numbers

You are given two numbers a and b and you should return their sum.

Examples:

Input: a = 4, b = 9

Output: 13

Explanation:
The sum of a and b is 4 + 9, which is 13.

This is the challenge statement. It explains what the challenge asks us to do and provides some examples to make sure we understand the statement.

Each challenge gives us some input and asks us to write some code that successfully takes that input and uses it to produce some desired output.

In this case, the input is two numbers a and b and the output is their sum.

The class:

If you look at the code editor, you will see that everything is wrapped up inside a class:

class Solution {

}

You don't need to know anything about classes at this point, we will study them in future lessons. Just leave that code untouched.

The method:

Inside this class, we will always be provided with a method. Inside this method is where we should write our solution.

In our case the method is:

sum(a, b) {
    // Your solution goes here
}

A method is just a function inside a class. When defining methods, we do not use the keyword function in the method's header.

Parameters and return:

This method's parameters will always match the input described in the challenge's statement. In our case, the parameters are a and b, the two numbers we are given.

The method should return a value which represents the desired output described in the challenge's statement. In our case, it should return a + b.

Assignment:

Follow the Coding Tutorial and let's solve our first coding challenge: Sum of Two Numbers

Understanding the Problem

The core challenge of this problem is to correctly implement a function that takes two numbers as input and returns their sum. This is a fundamental problem that helps in understanding how to handle basic arithmetic operations in programming.

Common applications of this problem include scenarios where you need to perform simple calculations, such as adding prices, scores, or any other numerical values.

Potential pitfalls include not correctly handling non-numeric inputs or misunderstanding the problem requirements.

Approach

To solve this problem, we need to think about the simplest way to add two numbers. The naive solution is straightforward: simply use the addition operator.

However, let's discuss why this is optimal and if there are any other approaches:

Naive Solution: Directly add the two numbers using the + operator. This is optimal because the addition operation is a basic arithmetic operation with constant time complexity O(1).

Algorithm

Here is a step-by-step breakdown of the algorithm:

Take two input numbers, a and b.
Return the sum of a and b.

Code Implementation

Below is the JavaScript implementation of the solution:

class Solution {
    // Method to return the sum of two numbers
    sum(a, b) {
        // Return the sum of a and b
        return a + b;
    }
}

Explanation of the code:

The sum method takes two parameters, a and b.
It returns the result of adding a and b.

Complexity Analysis

The time complexity of this solution is O(1) because the addition operation takes constant time.

The space complexity is also O(1) as we are not using any additional space that grows with the input size.

Edge Cases

Potential edge cases include:

Both numbers are zero: a = 0, b = 0. The output should be 0.
One number is negative: a = -5, b = 10. The output should be 5.
Both numbers are negative: a = -3, b = -7. The output should be -10.

Each of these cases should be tested to ensure the function handles them correctly.

Testing

To test the solution comprehensively, consider the following test cases:

const solution = new Solution();

console.log(solution.sum(4, 9)); // Expected output: 13
console.log(solution.sum(0, 0)); // Expected output: 0
console.log(solution.sum(-5, 10)); // Expected output: 5
console.log(solution.sum(-3, -7)); // Expected output: -10

These test cases cover a variety of scenarios, from simple positive numbers to edge cases involving zero and negative numbers.

Thinking and Problem-Solving Tips

When approaching such problems, consider the following tips:

Understand the problem requirements thoroughly before starting to code.
Think about the simplest and most efficient way to solve the problem.
Consider edge cases and test your solution against them.
Practice similar problems to improve your problem-solving skills.

Conclusion

In this blog post, we discussed how to solve the problem of summing two numbers using JavaScript. We covered the problem definition, approach, algorithm, code implementation, complexity analysis, edge cases, and testing. Understanding and solving such problems is crucial for developing strong programming skills.

We encourage you to practice and explore further to enhance your understanding and proficiency.

Additional Resources

For further reading and practice, consider the following resources: