Heap Sort

HeapSort.swift

import Foundation

var A = [4, 10, 14, 7, 9, 3, 2, 8, 1, 16]

func left(_ i: Int) -> Int {
    return i * 2 + 1
}

func right(_ i: Int) -> Int {
    return i * 2 + 1 + 1
}

func parent(_ i: Int) -> Int {
    return i/2
}

func maxHeapify(_ i: Int) {
    let l = left(i)
    let r = right(i)
    var largest = i
    if l < A.count {
        if A[l] > A[i] {
            largest = l
        }
    }
    if r < A.count {
        if A[r] > A[largest] {
            largest = r
        }
    }
    if largest != i {
        let temp = A[i]
        A[i] = A[largest]
        A[largest] = temp
        maxHeapify(largest)
    }
}

func minHeapify(_ i: Int) {
    let l = left(i)
    let r = right(i)
    var smallest = i
    if l < A.count {
        if A[l] < A[i] {
            smallest = l
        }
    }
    if r < A.count {
        if A[r] < A[smallest] {
            smallest = r
        }
    }
    if smallest != i {
        let temp = A[i]
        A[i] = A[smallest]
        A[smallest] = temp
        minHeapify(smallest)
    }
}


func solution() {
    print(A)
    for i in (0...A.count/2).reversed() {
        maxHeapify(i)
    }
    print(A)
    for i in (0...A.count/2).reversed() {
        minHeapify(i)
    }
    print(A)
}

solution()