2237. Count Positions on Street With Required Brightness π
Description
You are given an integer n
. A perfectly straight street is represented by a number line ranging from 0
to n - 1
. You are given a 2D integer array lights
representing the street lamp(s) on the street. Each lights[i] = [positioni, rangei]
indicates that there is a street lamp at position positioni
that lights up the area from [max(0, positioni - rangei), min(n - 1, positioni + rangei)]
(inclusive).
The brightness of a position p
is defined as the number of street lamps that light up the position p
. You are given a 0-indexed integer array requirement
of size n
where requirement[i]
is the minimum brightness of the ith
position on the street.
Return the number of positions i
on the street between 0
and n - 1
that have a brightness of at least requirement[i]
.
Example 1:
Input: n = 5, lights = [[0,1],[2,1],[3,2]], requirement = [0,2,1,4,1] Output: 4 Explanation: - The first street lamp lights up the area from [max(0, 0 - 1), min(n - 1, 0 + 1)] = [0, 1] (inclusive). - The second street lamp lights up the area from [max(0, 2 - 1), min(n - 1, 2 + 1)] = [1, 3] (inclusive). - The third street lamp lights up the area from [max(0, 3 - 2), min(n - 1, 3 + 2)] = [1, 4] (inclusive). - Position 0 is covered by the first street lamp. It is covered by 1 street lamp which is greater than requirement[0]. - Position 1 is covered by the first, second, and third street lamps. It is covered by 3 street lamps which is greater than requirement[1]. - Position 2 is covered by the second and third street lamps. It is covered by 2 street lamps which is greater than requirement[2]. - Position 3 is covered by the second and third street lamps. It is covered by 2 street lamps which is less than requirement[3]. - Position 4 is covered by the third street lamp. It is covered by 1 street lamp which is equal to requirement[4]. Positions 0, 1, 2, and 4 meet the requirement so we return 4.
Example 2:
Input: n = 1, lights = [[0,1]], requirement = [2] Output: 0 Explanation: - The first street lamp lights up the area from [max(0, 0 - 1), min(n - 1, 0 + 1)] = [0, 0] (inclusive). - Position 0 is covered by the first street lamp. It is covered by 1 street lamp which is less than requirement[0]. - We return 0 because no position meets their brightness requirement.
Constraints:
1 <= n <= 105
1 <= lights.length <= 105
0 <= positioni < n
0 <= rangei <= 105
requirement.length == n
0 <= requirement[i] <= 105
Solutions
Solution 1
1 2 3 4 5 6 7 8 9 10 |
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1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 |
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1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 |
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1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 |
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