1109. Corporate Flight Bookings

Problem

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 * 10^4

• 1 <= bookings.length <= 2 * 10^4

• bookings[i].length == 3

• 1 <= firsti <= lasti <= n

• 1 <= seatsi <= 10^4

Solution (Java)

class Solution {
    public int[] corpFlightBookings(int[][] bookings, int n) {
        int[] ret = new int[n];
        for (int[] booking : bookings) {
            ret[booking[0] - 1] += booking[2];
            if (booking[1] < n) {
                ret[booking[1]] -= booking[2];
            }
        }
        for (int i = 1; i < n; ++i) {
            ret[i] += ret[i - 1];
        }
        return ret;
    }
}

Explain:

nope.

Complexity:

• Time complexity : O(n).
• Space complexity : O(n).