643 Maximum Average Subarray I 1

Joel Castillo Espinosa 2

DESCRIPTION

You are given an integer array nums consisting of n elements, and an integer k.

Find a contiguous subarray whose length is equal to k that has the maximum average value and return this value. Any answer with a calculation error less than $10^{-5}$ will be accepted.

Examples

  • Example 1:
    • Input: nums = [1,12,-5,-6,50,3], k = 4
    • Output: 12.75000
    • Explanation: Maximum average is (12 - 5 - 6 + 50) / 4 = 51 / 4 = 12.75
  • Example 2:
    • Input: nums = [5], k = 1
    • Output: 5.00000

Constraints:

  • n == nums.length

  • 1 ≤ k ≤ n ≤ $10^{5}$

  • $-10^{4}$ ≤ nums[i] ≤ $10^{4}$

SOLUTION 3

max_ave <- function(nums,k){
  max_v <- mean(nums[1:k]) # define the first max for the k-first elements in nums
  # case if the k == length of nums
  if (k == length(nums)){
    return(max_v) 
  } else {
    # in each iteration, calculate the mean for the subarray nums[i:i+k-1]
    max_ext <- length(nums) - k + 1 
    for (i in 2:max_ext) { # max_ext: max value to get a k-length subarray 
      ext <- i+k-1
      # calculate the mean 
      value <- mean(nums[i:ext])
      # and compare the mean with the max 
      max_v <- ifelse(max_v > value, max_v, value)
    }
    return(max_v)
  }
}

Examples using the function

We can use the examples presented before.

max_ave(nums = c(5,2), k = 1)

## [1] 5

max_ave(nums = c(1,12,-5,-6,50,3), k = 4)

## [1] 12.75

  1. This problem is originally from LeetCode, you can find it in Leetcode. ↩

  2. Email: jocastillo@colmex.mx. For more content visit my website: https://joelcastillo.netlify.app
    If you have any questions or suggestions, I’d be grateful to hear from you. ↩

  3. This solution is entirely my own work. It was developed using R version 4.4.1 (2024-06-14 ucrt). ↩