quick-sort.js

const pivot = (arr, start = 0, end = arr.length - 1) => {
    const swap = (arr, idx1, idx2) => {
        [arr[idx1], arr[idx2]] = [arr[idx2], arr[idx1]];
    };

    // We are assuming the pivot is always the first element
    let pivot = arr[start];
    let swapIdx = start;

    for (let i = start + 1; i <= end; i++) {
        if (pivot > arr[i]) {
            swapIdx++;
            // let temp = arr[i];
            // arr[i] = pivot;
            // pivot = temp;
            swap(arr, swapIdx, i);
        }
    }

    // Swap the pivot from the start the swapPoint
    swap(arr, start, swapIdx);
    return swapIdx;
}

let totalIterations = 0;
const quickSort = (arr, left = 0, right = arr.length - 1) => {
    totalIterations++;
    if (left < right) {
        let pivotIndex = pivot(arr, left, right) //3
        //left
        quickSort(arr, left, pivotIndex - 1);
        //right
        quickSort(arr, pivotIndex + 1, right);
    }
    return arr;
}

console.log(quickSort([100, -3, 2, 4, 6, 9, 1, 2, 5, 3, 23]))
console.log('totalIterations', totalIterations);
totalIterations = 0;
console.log(quickSort([10, 53, 0, 34, 390, -2, 45]));
console.log('totalIterations', totalIterations);




// [4,6,9,1,2,5,3]
// [3,2,1,4,6,9,5]
//        4
//  3,2,1    6,9,5
//      3      6
//  2,1      5  9
//    2
//  1