動機
太久沒打真的會忘記 這是prefix sum阿
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 = 5Output: [10,55,45,25,25]Explanation:Flight labels: 1 2 3 4 5Booking 1 reserved: 10 10Booking 2 reserved: 20 20Booking 3 reserved: 25 25 25 25Total seats: 10 55 45 25 25Hence, answer = [10,55,45,25,25]
Example 2:
Input: bookings = [[1,2,10],[2,2,15]], n = 2Output: [10,25]Explanation:Flight labels: 1 2Booking 1 reserved: 10 10Booking 2 reserved: 15Total seats: 10 25Hence, answer = [10,25]
Constraints:
1 <= n <= 2 * 104
1 <= bookings.length <= 2 * 104
bookings[i].length == 3
1 <= firsti <= lasti <= n
1 <= seatsi <= 104
Sol
class Solution:
def corpFlightBookings(self, bookings: List[List[int]], n: int) -> List[int]:
res = [0] * (n+1)
for first, last, num in bookings:
res[first-1] += num
res[last] -= num
for i in range(1, len(res)):
res[i] += res[i-1]
return res[:-1]