[Algorithms] Quick Sort (Initial Pivot) - TypeScript Implementation

algorithm-quickSortInitialPivot.ts

/**
 *  @file algorithm-quickSortInitialPivot.ts - A TypeScript implementation of the Quick Sort algorithm using recursion and the first element of the input array as a pivot
 *  @author Avana Vana
 *  @desc Algorithmic complexity:
 *  - Time complexity: Ω(n log(n)), Θ(n log(n)), O(n^2)
 *  - Space complexity: O(n)
 */

/**
 *  @function quickSort
 *  @desc Sorts an input array according to the Quick Sort algorithm with recursion and the pivot set to the initial element and returns the sorted array
 *  @template T
 *  @param {T[]} arr - input array of type T
 *  @returns {T[]} Sorted input array
 */

function quickSort<T>(arr: T[]): T[] {
    if (arr.length <= 1) return arr;
    let pivot = arr[0], left: T[] = [], right: T[] = [];
  
    for (let i = 1; i < arr.length; i++) {
        if (arr[i] < pivot) left.push(arr[i]);
        else right.push(arr[i]);
    }
  
    return [ ...quickSort(left), pivot, quickSort(right) ];
}

quickSort([ 3, 7, 5, 2, 6, 1, 0, 4 ]);

// > [ 0, 1, 2, 3, 4, 5, 6, 7 ]