medium

Sort Employees by Rating (Descending)

Sort a list of employees by rating from highest to lowest using selection sort.

1. Define the problem

Sort Employees by Rating (Descending)

Given an array ratings of employee performance scores, sort it in descending order (highest rating first) using selection sort. The mechanic is the same as ascending selection sort, but each pass looks for the maximum remaining value instead of the minimum, and swaps it to the front of the unsorted region. Return the sorted array.

Constraints

  • 1 ≤ ratings.length ≤ 1000
  • 0 ≤ ratingsi ≤ 100

Example

Inputratings = [72, 95, 68, 88]
Output[95, 88, 72, 68]

Explanation Each pass finds the largest remaining rating and swaps it to the front: 95, then 88, then 72, leaving 68 in place.

2. Know the words first

In plain terms

Descending order
Each value is less than or equal to the one before it, largest first.
Comparator
The rule a sort uses to decide which of two values should come first — flipping the comparison direction flips the whole sort.
3. Visualize the solution

Scan for the maximum, then swap it to the front

Scan for the maximum, then swap it to the front
Statuspass 1

Scan all 4 ratings — the maximum is 95 at index 1.

What happens in this step

ratings = [72, 95, 68, 88], sortedEnd = 0, max so far = 72 (index 0)

  idx 1: 95 > 72  →  new max = 95 at index 1
  idx 2: 68 > 95  →  no
  idx 3: 88 > 95  →  no

95 at index 1 beats every other candidate — maxIndex settles on 1.
Step 1 of 5

Steps to visualize

  1. Set sortedEnd to 0.
  2. Scan the unsorted region, tracking the index of the largest value seen instead of the smallest.
  3. Swap that maximum into index sortedEnd.
  4. Move sortedEnd forward and repeat.
4. Walk through the code

Walk through the code

Same walkthrough, now with the code. Press Next to move one step and watch which lines run.

Scan for the maximum, then swap it to the front
Statuspass 1

Scan all 4 ratings — the maximum is 95 at index 1.

What happens in this step

ratings = [72, 95, 68, 88], sortedEnd = 0, max so far = 72 (index 0)

  idx 1: 95 > 72  →  new max = 95 at index 1
  idx 2: 68 > 95  →  no
  idx 3: 88 > 95  →  no

95 at index 1 beats every other candidate — maxIndex settles on 1.
Step 1 of 5
5. Solution

Solution

solution.tsTypeScript
function sortRatingsDescending(ratings) {
  const arr = ratings.slice();

  for (let sortedEnd = 0; sortedEnd < arr.length - 1; sortedEnd++) {
    let maxIndex = sortedEnd;

    for (let scan = sortedEnd + 1; scan < arr.length; scan++) {
      if (arr[scan] > arr[maxIndex]) {
        maxIndex = scan;
      }
    }

    if (maxIndex !== sortedEnd) {
      const temp = arr[sortedEnd];
      arr[sortedEnd] = arr[maxIndex];
      arr[maxIndex] = temp;
    }
  }

  return arr;
}
Time
O(n^2)
Space
O(n)
6. Test cases

Test cases

InputExpectedCovers
ratings = [72, 95, 68, 88][95, 88, 72, 68]example from the docstring
ratings = [90, 80, 70][90, 80, 70]already in descending order
ratings = [10, 20, 30, 40][40, 30, 20, 10]fully ascending input needs a complete reversal
ratings = [50, 50, 80, 50][80, 50, 50, 50]duplicate ratings mixed with a distinct high value
ratings = [77][77]smallest valid input, a single rating
ratings = [60, 60, 60][60, 60, 60]every rating is identical
ratings = [40, 90][90, 40]boundary case, exactly two ratings out of order

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