package main

import (
	"fmt"
)

func swap(A []int, a, b int) {
	var c int
	c = A[a]
	A[a] = A[b]
	A[b] = c
}

func heap(A []int, i, delim int) {

	var left int = 2*i + 1
	var right int = 2*i + 2

	if right >= delim {
		return
	}

	if (A[left] > A[right]) && (A[left] > A[i]) {
		swap(A, i, left)
		heap(A, left, delim)
	} else if A[right] > A[i] {
		swap(A, i, right)
		heap(A, right, delim)
	}
}

func heapsort(A []int) {
	var length int = len(A)

	for i := length/2 - 1; i >= 0; i-- {
		heap(A, i, length-1)
	}
	for i := length - 1; i > 0; i-- {
		swap(A, i, 0)
		heap(A, 0, i)
	}
}

func test(ok []int) {
	ok[1] = 100
}

func main() {
	sample := []int{9, 23, 24, 20, 18, 14, 17, 13, 15, 11, 10, 5, 7, 3, 2, 20}
	heapsort(sample)
	fmt.Println(sample)
}