Introduction

In this blog post, we will explore how to solve the LeetCode problem "714" 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

You are given an array prices where prices[i] is the price of a given stock on the ith day, and an integer fee representing a transaction fee. Find the maximum profit you can achieve. You may complete as many transactions as you like, but you need to pay the transaction fee for each transaction. Note: You may not engage in multiple transactions simultaneously (i.e., you must sell the stock before you buy again). The transaction fee is only charged once for each stock purchase and sale. Example 1: Input: prices = [1,3,2,8,4,9], fee = 2 Output: 8 Explanation: The maximum profit can be achieved by: - Buying at prices[0] = 1 - Selling at prices[3] = 8 - Buying at prices[4] = 4 - Selling at prices[5] = 9 The total profit is ((8 - 1) - 2) + ((9 - 4) - 2) = 8. Example 2: Input: prices = [1,3,7,5,10,3], fee = 3 Output: 6 Constraints: 1 <= prices.length <= 5 104 1 <= prices[i] < 5 104 0 <= fee < 5 * 104

Explanation

Here's a breakdown of the solution and the code:

• High-Level Approach:

  • Use Dynamic Programming to track the maximum profit at each day, considering two states: holding a stock or not holding a stock.
  • Iterate through the prices, updating the profit for both states based on the current price and the transaction fee.
  • The final result is the maximum profit when not holding a stock on the last day.

• Complexity:

  • Runtime: O(n), where n is the length of the prices array.
  • Storage: O(1) - constant extra space.

Code

    def maxProfit(prices, fee):
    """
    Calculates the maximum profit achievable with transaction fees.

    Args:
        prices (list[int]): The prices of the stock on each day.
        fee (int): The transaction fee.

    Returns:
        int: The maximum profit.
    """

    cash = 0  # Represents the maximum profit when not holding a stock
    hold = -prices[0]  # Represents the maximum profit when holding a stock

    for i in range(1, len(prices)):
        cash = max(cash, hold + prices[i] - fee)  # Sell stock if profitable
        hold = max(hold, cash - prices[i])  # Buy stock if profitable

    return cash