A.5.8.1: Heap Sort

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A.5.8.1: Heap Sort
In D.7 we mentioned heap sort that runs in O(nlogn) time. Now that we've covered heaps we can look at this algo again.
Heap Sort
Runtime: O(nlogn)
Space: O(1)
Sort In-Place: Yes
Stable: Yes
Attributes
good space complexity
not favored compared to quicksort
def heapify(arr, n, i):
    # Find largest among root and children
    largest = i
    l = 2 * i + 1
    r = 2 * i + 2
​
    if l < n and arr[i] < arr[l]:
        largest = l
​
    if r < n and arr[largest] < arr[r]:
        largest = r
​
    # If root is not largest, swap with largest and continue heapifying
    if largest != i:
        arr[i], arr[largest] = arr[largest], arr[i]
        heapify(arr, n, largest)
​
​
def heapSort(arr):
    n = len(arr)
​
    # Build max heap
    for i in range(n//2, -1, -1):
        heapify(arr, n, i)
​
    for i in range(n-1, 0, -1):
        # Swap
        arr[i], arr[0] = arr[0], arr[i]
​
        # Heapify root element
        heapify(arr, i, 0)
​
​
arr = [1, 12, 9, 5, 6, 10]
heapSort(arr)
n = len(arr)
print("Sorted array is")
for i in range(n):
    print("%d " % arr[i], end='')
From: https://www.programiz.com/dsa/heap-sort​
A.5.8: Heaps
A.6: Binary Search
Last modified 3mo ago
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Heap Sort