Introduction

In this blog post, we will explore how to solve the LeetCode problem "2806" using AI. LeetCode is a popular platform for preparing for coding interviews, and with the help of AI tools like Chatmagic, we can generate solutions quickly and efficiently - helping you pass the interviews and get the job offer without having to study for months.

Problem Statement

Initially, you have a bank account balance of 100 dollars. You are given an integer purchaseAmount representing the amount you will spend on a purchase in dollars, in other words, its price. When making the purchase, first the purchaseAmount is rounded to the nearest multiple of 10. Let us call this value roundedAmount. Then, roundedAmount dollars are removed from your bank account. Return an integer denoting your final bank account balance after this purchase. Notes: 0 is considered to be a multiple of 10 in this problem. When rounding, 5 is rounded upward (5 is rounded to 10, 15 is rounded to 20, 25 to 30, and so on). Example 1: Input: purchaseAmount = 9 Output: 90 Explanation: The nearest multiple of 10 to 9 is 10. So your account balance becomes 100 - 10 = 90. Example 2: Input: purchaseAmount = 15 Output: 80 Explanation: The nearest multiple of 10 to 15 is 20. So your account balance becomes 100 - 20 = 80. Example 3: Input: purchaseAmount = 10 Output: 90 Explanation: 10 is a multiple of 10 itself. So your account balance becomes 100 - 10 = 90. Constraints: 0 <= purchaseAmount <= 100

Explanation

Here's the breakdown of the solution:

• Rounding: Determine the nearest multiple of 10 to purchaseAmount. If the last digit is less than 5, round down; otherwise, round up.
• Balance Update: Subtract the rounded amount from the initial balance (100).

• Return: Return the updated balance.

• Runtime Complexity: O(1), Storage Complexity: O(1)

Code

    def account_balance_after_purchase(purchaseAmount: int) -> int:
    """
    Calculates the final bank account balance after a purchase, where the purchase amount is rounded to the nearest multiple of 10.

    Args:
        purchaseAmount: The amount to spend on a purchase.

    Returns:
        The final bank account balance after the purchase.
    """

    remainder = purchaseAmount % 10

    if remainder < 5:
        roundedAmount = purchaseAmount - remainder
    else:
        roundedAmount = purchaseAmount + (10 - remainder)

    return 100 - roundedAmount