Medium

K Radius Subarray Averages

LAB

For each index, return the integer average of the subarray centered there with radius k, or -1 when the full window does not fit.

EXAMPLES

Example 1

Input
{
  "nums": [
    7,
    4,
    3,
    9,
    1,
    8,
    5,
    2,
    6
  ],
  "k": 3
}

Output
[
  -1,
  -1,
  -1,
  5,
  4,
  4,
  -1,
  -1,
  -1
]

FUNCTION SHAPE

nums: intArrayk: int→intArray

SOLUTION NOTE

Note: k in this case refers to one side of the array, so the window is of size 2k+1. We want to update index i-k in res, because that's the midpoint index of the window.

Reveal reference solution +

pythonREFERENCE

def getAverages(self, nums: List[int], k: int) -> List[int]:
    n = len(nums)
    res = [-1] * n
    sum_ = 0

    for i in range(n):
        sum_ += nums[i]

        if i >= 2 * k:
            res[i - k] = sum_ // (2 * k + 1)
            sum_ -= nums[i - 2 * k]

    return res

TimeO(n)

SpaceO(n)

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