maxHeapify an array

maxHeapify.ts

function maxHeapify(arr: any): any {
    arr.push(arr[0]) // push 0th position to end
    let heap = arr
    let cur = Math.floor(heap.length - 1)/2
    while (cur > 0) { // ignore the 0th index bc we pushed that value to the end
        // go from the half way mark down to 1
        let i = cur // start a the half way and work back up to 1
        // while left child position is less than length of heap
        while (2 * i < heap.length) { // while cur has a left child
            if (2 * i + 1 < heap.length && // if cur has a right child too
            heap[2 * i  + 1] < heap[2 * i] && // if right child < left child
            heap[i] < heap[2 * i + 1]) { // cur < right
                // swap cur with right child
                let tmp = heap[i]
                heap[i] = heap[2 * i + 1]
                heap[2 * i + 1] = tmp
                i = 2 * i + 1
            } else if (heap[i] < heap[2 * i]) { // only has left child
                                                    // cur < left
                // swap cur with left child 
                let tmp = heap[i]
                heap[i] = heap[2 * i]
                heap[2 * i] = tmp
                i = 2 * i
            } else {
                break;
            }
        }
        cur = cur - 1
    }
    return heap
}