Introduction

In this blog post, we will explore how to solve the LeetCode problem "1109" 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 are n flights that are labeled from 1 to n. You are given an array of flight bookings bookings, where bookings[i] = [firsti, lasti, seatsi] represents a booking for flights firsti through lasti (inclusive) with seatsi seats reserved for each flight in the range. Return an array answer of length n, where answer[i] is the total number of seats reserved for flight i. Example 1: Input: bookings = [[1,2,10],[2,3,20],[2,5,25]], n = 5 Output: [10,55,45,25,25] Explanation: Flight labels: 1 2 3 4 5 Booking 1 reserved: 10 10 Booking 2 reserved: 20 20 Booking 3 reserved: 25 25 25 25 Total seats: 10 55 45 25 25 Hence, answer = [10,55,45,25,25] Example 2: Input: bookings = [[1,2,10],[2,2,15]], n = 2 Output: [10,25] Explanation: Flight labels: 1 2 Booking 1 reserved: 10 10 Booking 2 reserved: 15 Total seats: 10 25 Hence, answer = [10,25] Constraints: 1 <= n <= 2 104 1 <= bookings.length <= 2 104 bookings[i].length == 3 1 <= firsti <= lasti <= n 1 <= seatsi <= 104

Explanation

Here's an efficient solution to the flight booking problem:

• Difference Array: Use a difference array to efficiently track the changes in seat reservations across flights. Instead of iterating through the range of each booking, we only update the start and end points of the range.

• Prefix Sum: After processing all bookings, compute the prefix sum of the difference array to obtain the actual number of seats reserved for each flight.

• Runtime Complexity: O(n + m), where n is the number of flights and m is the number of bookings.

• Storage Complexity: O(n), where n is the number of flights (for the answer array).

Code

    def corpFlightBookings(bookings, n):
    """
    Calculates the total number of seats reserved for each flight.

    Args:
        bookings: A list of flight bookings, where each booking is a list [firsti, lasti, seatsi].
        n: The number of flights.

    Returns:
        A list of length n, where answer[i] is the total number of seats reserved for flight i.
    """

    answer = [0] * n  # Initialize the answer array with zeros

    # Use the difference array technique to update the seat reservations
    for first, last, seats in bookings:
        answer[first - 1] += seats  # Add seats at the start of the range
        if last < n:
            answer[last] -= seats  # Subtract seats after the end of the range

    # Calculate the prefix sum to get the actual number of seats for each flight
    for i in range(1, n):
        answer[i] += answer[i - 1]

    return answer