README.md

1471. The k Strongest Values in an Array

Given an array of integers arr and an integer k.

A value arr[i] is said to be stronger than a value arr[j] if |arr[i] - m| > |arr[j] - m| where m is the median of the array. If |arr[i] - m| == |arr[j] - m|, then arr[i] is said to be stronger than arr[j] if arr[i] > arr[j].

Return a list of the strongest k values in the array. return the answer in any arbitrary order.

Median is the middle value in an ordered integer list. More formally, if the length of the list is n, the median is the element in position ((n - 1) / 2) in the sorted list (0-indexed).

• For arr = [6, -3, 7, 2, 11], n = 5 and the median is obtained by sorting the array arr = [-3, 2, 6, 7, 11] and the median is arr[m] where m = ((5 - 1) / 2) = 2. The median is 6.
• For arr = [-7, 22, 17, 3], n = 4 and the median is obtained by sorting the array arr = [-7, 3, 17, 22] and the median is arr[m] where m = ((4 - 1) / 2) = 1. The median is 3.

Example 1:

Input: arr = [1,2,3,4,5], k = 2
Output: [5,1]
Explanation: Median is 3, the elements of the array sorted by the strongest are [5,1,4,2,3]. The strongest 2 elements are [5, 1]. [1, 5] is also accepted answer.
Please note that although |5 - 3| == |1 - 3| but 5 is stronger than 1 because 5 > 1.

Example 2:

Input: arr = [1,1,3,5,5], k = 2
Output: [5,5]
Explanation: Median is 3, the elements of the array sorted by the strongest are [5,5,1,1,3]. The strongest 2 elements are [5, 5].

Example 3:

Input: arr = [6,7,11,7,6,8], k = 5
Output: [11,8,6,6,7]
Explanation: Median is 7, the elements of the array sorted by the strongest are [11,8,6,6,7,7].
Any permutation of [11,8,6,6,7] is accepted.

Example 4:

Input: arr = [6,-3,7,2,11], k = 3
Output: [-3,11,2]

Example 5:

Input: arr = [-7,22,17,3], k = 2
Output: [22,17]

Constraints:

• 1 <= arr.length <= 10^5
• -10^5 <= arr[i] <= 10^5
• 1 <= k <= arr.length

Solutions (Ruby)

1. Sort

# @param {Integer[]} arr
# @param {Integer} k
# @return {Integer[]}
def get_strongest(arr, k)
  arr.sort!
  m = (arr.size - 1) / 2
  i = 0
  j = arr.size - 1
  ret = []

  while ret.size < k
    if (arr[i] - arr[m]).abs > (arr[j] - arr[m]).abs
      ret.push(arr[i])
      i += 1
    else
      ret.push(arr[j])
      j -= 1
    end
  end

  ret
end

Solutions (Rust)

1. Sort

impl Solution {
    pub fn get_strongest(mut arr: Vec<i32>, k: i32) -> Vec<i32> {
        arr.sort_unstable();
        let m = (arr.len() - 1) / 2;
        let mut i = 0;
        let mut j = arr.len() - 1;
        let mut ret = vec![];

        while ret.len() < k as usize {
            if (arr[i] - arr[m]).abs() > (arr[j] - arr[m]).abs() {
                ret.push(arr[i]);
                i += 1;
            } else {
                ret.push(arr[j]);
                j -= 1;
            }
        }

        ret
    }
}