1109 Flight Booking

1109 Flight Booking#

Problem#

There are n flights that are labeled from 1 to n.

You are given an array of flight bookings bookings, where bookings[i] = [first_i, last_i, seats_i] represents a booking for flights first_i through last_i (inclusive) with seats_i 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.

Examples#

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]

Constraint#

1 <= n <= 2 * 1E4
1 <= bookings.length <= 2 * 1E4
bookings[i].length == 3
1 <= firsti <= lasti <= n
1 <= seatsi <= 1E4

Analysis#

Solution#

def rangeAddition(length, bookings):
    difference = [0 for i in range(length)]
    for book in bookings:
        # note this indexes are 1-based
        start, end, addition = book
        difference[start-1] += addition
        if end < length:
            difference[end] -= addition
    
    # reconstruct array
    res = [0 for i in range(length)]
    res[0] = difference[0]
    i = 1
    while i < length:
        res[i] = res[i-1] + difference[i]
        i += 1
    return res

length = 5
bookings = [[1,2,10],[2,3,20],[2,5,25]]
print(rangeAddition(length, bookings))

length = 2
bookings = [[1,2,10],[2,2,15]]
print(rangeAddition(length, bookings))

[10, 55, 45, 25, 25]
[10, 25]
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