#!/usr/bin/ruby

#
## http://rosettacode.org/wiki/Sorting_algorithms/Heapsort
#

func siftDown(a, start, end) {
    var root = start;
    while ((2*root + 1) <= end) {
        var child = (2*root + 1);
        if ((child+1 <= end) && (a[child] < a[child + 1])) {
            child += 1;
        }
        if (a[root] < a[child]) {
            a[child, root] = a[root, child];
            root = child;
        } else {
            return();
        }
    }
}
 
func heapify(a, count) {
    var start = ((count - 2) / 2);
    while (start >= 0) {
        siftDown(a, start, count-1);
        start -= 1;
    }
}
 
func heapSort(a, count) {
    heapify(a, count);
    var end = (count - 1);
    while (end > 0) {
        a[0, end] = a[end, 0];
        end -= 1;
        siftDown(a, 0, end)
    }
    return a
}
 
var numbers = [7,6,5,9,8,4,3,1,2,0];
say heapSort(numbers, numbers.len);
 
var strs = ["John", "Kate", "Zerg", "Alice", "Joe", "Jane"];
say heapSort(strs, strs.len);
