Exercise: Price After Discount in JavaScript

Understanding the Problem

The core challenge of this problem is to correctly apply a percentage discount to a given price. This is a common task in e-commerce and retail applications where discounts are frequently applied to products.

Potential pitfalls include incorrect calculations due to misunderstanding percentage operations or arithmetic errors.

Approach

To solve this problem, we need to follow these steps:

Calculate the discount amount by multiplying the original price by the discount percentage divided by 100.
Subtract the discount amount from the original price to get the final price after the discount.

Let's break down the steps:

Discount Amount = (Price * Discount) / 100
Final Price = Price - Discount Amount

Algorithm

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

Read the original price and discount percentage.
Calculate the discount amount using the formula: discountAmount = (price * discount) / 100.
Subtract the discount amount from the original price to get the final price: finalPrice = price - discountAmount.
Print the final price.

Code Implementation

// Define the original price and discount percentage
let price = 150; // Example price
let discount = 10; // Example discount percentage

// Calculate the discount amount
let discountAmount = (price * discount) / 100;

// Calculate the final price after discount
let finalPrice = price - discountAmount;

// Print the final price
console.log(finalPrice); // Output: 135

Complexity Analysis

The time complexity of this solution is O(1) because the calculations involve a constant number of operations regardless of the input values. The space complexity is also O(1) as we are using a fixed amount of extra space for variables.

Edge Cases

Consider the following edge cases:

If the discount is 0%, the final price should be the same as the original price.
If the discount is 100%, the final price should be 0.
If the price is 0, the final price should also be 0 regardless of the discount percentage.

Examples:

Price: 200, Discount: 0% -> Final Price: 200
Price: 200, Discount: 100% -> Final Price: 0
Price: 0, Discount: 50% -> Final Price: 0

Testing

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

Simple cases with non-zero price and discount.
Edge cases as discussed above.
Cases with large values to ensure no overflow or precision issues.

Example test cases:

// Test case 1: Simple case
let price1 = 150;
let discount1 = 10;
console.log((price1 - (price1 * discount1) / 100)); // Expected output: 135

// Test case 2: No discount
let price2 = 200;
let discount2 = 0;
console.log((price2 - (price2 * discount2) / 100)); // Expected output: 200

// Test case 3: Full discount
let price3 = 200;
let discount3 = 100;
console.log((price3 - (price3 * discount3) / 100)); // Expected output: 0

// Test case 4: Zero price
let price4 = 0;
let discount4 = 50;
console.log((price4 - (price4 * discount4) / 100)); // Expected output: 0

Thinking and Problem-Solving Tips

When approaching such problems, it is essential to:

Understand the mathematical operations involved.
Break down the problem into smaller, manageable steps.
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 calculate the price after applying a discount. 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 problem-solving skills in programming.

Keep practicing and exploring further to enhance your skills!

Additional Resources

For further reading and practice, consider the following resources: