Heap sort algorithm, using the binary heap, and bitmask operators

heapsort.py

class Heap:

    def __init__(self, arr):
        self.cont = arr
        self.size = len(self.cont) - 1
        self.buildheap()

    def left(self, i):
        return (i << 1) + 1
    def right(self, i):
        return (i << 1) + 2
    def parent(self, i):
        return (i - 1) >> 1

    def buildheap(self):
        for i in range(self.size >> 1, -1, -1):
            self.heapify(i)

    def heapify(self, i):
        l = self.left(i)
        r = self.right(i)

        largest = i
        if l <= self.size and self.cont[l] > self.cont[i]:
            largest = l
        if r <= self.size and self.cont[r] > self.cont[largest]:
            largest = r

        if largest != i:
            self.cont[i], self.cont[largest] = self.cont[largest], self.cont[i]
            self.heapify(largest)

def heapsort(arr):
    h = Heap(arr)
    for i in range(h.size, 0, -1):
        h.cont[0], h.cont[i] = h.cont[i], h.cont[0]
        h.size -= 1
        h.heapify(0)

    return h.cont

if __name__ == '__main__':
    arr = [5, 13, 2, 25, 7, 17, 20, 8, 4]
    print(heapsort(arr))