【重点】【差分数组】1109.航班预订统计

题目

Python

重点是读懂题目，标准差分数组解法！！！
参考答案：https://leetcode.cn/problems/corporate-flight-bookings/solutions/968214/hang-ban-yu-ding-tong-ji-by-leetcode-sol-5pv8/?envType=study-plan-v2&envId=labuladong-algorithm-note

差分数组的性质这段话想了半天,终于理解了,为了仅仅让原数组下标在[l,r]区间内的元素值增加 inc
首先需要将差分数组d[l]位置加 inc,这样下标 >= l 位置的元素都获得inc增量
其次,为了不影响原数组中下标大于 r 的元素,需要在d[r + 1]处减去inc,使得原数组下标 > r 的元素值不变.

class Solution:
    def corpFlightBookings(self, bookings: List[List[int]], n: int) -> List[int]:
        diff = [0] * n
        for book in bookings:
            first, last, seats = book[0], book[1], book[2]
            diff[first-1] += seats  # 第first-1索引趟航班增加seats人数
            if last < n:
                diff[last] -= seats # seats人数只截止到last-1趟航班, 所以从第[(last-1)+1]趟航班减少seats人数
        
        for i in range(1, n):
            diff[i] += diff[i-1]
        
        return diff