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Solving Leetcode Interviews in Seconds with AI: Grumpy Bookstore Owner

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3 min read

Introduction

In this blog post, we will explore how to solve the LeetCode problem "1052" 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

There is a bookstore owner that has a store open for n minutes. You are given an integer array customers of length n where customers[i] is the number of the customers that enter the store at the start of the ith minute and all those customers leave after the end of that minute. During certain minutes, the bookstore owner is grumpy. You are given a binary array grumpy where grumpy[i] is 1 if the bookstore owner is grumpy during the ith minute, and is 0 otherwise. When the bookstore owner is grumpy, the customers entering during that minute are not satisfied. Otherwise, they are satisfied. The bookstore owner knows a secret technique to remain not grumpy for minutes consecutive minutes, but this technique can only be used once. Return the maximum number of customers that can be satisfied throughout the day. Example 1: Input: customers = [1,0,1,2,1,1,7,5], grumpy = [0,1,0,1,0,1,0,1], minutes = 3 Output: 16 Explanation: The bookstore owner keeps themselves not grumpy for the last 3 minutes. The maximum number of customers that can be satisfied = 1 + 1 + 1 + 1 + 7 + 5 = 16. Example 2: Input: customers = [1], grumpy = [0], minutes = 1 Output: 1 Constraints: n == customers.length == grumpy.length 1 <= minutes <= n <= 2 * 104 0 <= customers[i] <= 1000 grumpy[i] is either 0 or 1.

Explanation

Here's an efficient solution to the problem, addressing the core requirements and constraints.

  • Calculate Initial Satisfaction: Compute the number of satisfied customers when the technique is not used at all (i.e., based on the initial grumpy array).
  • Sliding Window: Use a sliding window of size minutes to iterate through the customers and grumpy arrays. Within each window, calculate the additional customers that could be satisfied if the technique was applied during those minutes.
  • Maximize Satisfaction: Keep track of the maximum additional satisfaction achievable across all possible window positions. Add this maximum to the initial satisfaction to get the final result.

  • Runtime Complexity: O(n), where n is the length of the customers array. Storage Complexity: O(1)

Code

    def max_satisfied(customers, grumpy, minutes):
    """
    Calculates the maximum number of satisfied customers.

    Args:
        customers: A list of integers representing the number of customers.
        grumpy: A list of integers representing the grumpy status of the owner (0 or 1).
        minutes: The number of consecutive minutes the owner can be not grumpy.

    Returns:
        The maximum number of satisfied customers.
    """
    n = len(customers)
    initial_satisfied = 0
    for i in range(n):
        if grumpy[i] == 0:
            initial_satisfied += customers[i]

    max_additional_satisfied = 0
    current_additional_satisfied = 0

    for i in range(n):
        if grumpy[i] == 1:
            current_additional_satisfied += customers[i]

        if i >= minutes:
            if grumpy[i - minutes] == 1:
                current_additional_satisfied -= customers[i - minutes]

        max_additional_satisfied = max(max_additional_satisfied, current_additional_satisfied)

    return initial_satisfied + max_additional_satisfied

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