//
// example of recursion and sorting:
//
// 	selection sort
//
// main (test) program prompts for input
//
#include <iostream.h>


// precondition:  n >= 0, and a has at least n elements
// postcondition:  a[0] .. a[n-1] are "sorted" -- i.e., 
//	elements have been rearranged to be in nondecreasing order
void selectionSort(int a[], const int n);

// precondition:  n >= 1, n is size of array a
// postcondition:  return value is index in a of largest element
int findIndexOfLargest(const int a[], const int n);

// precondition:  none
// postcondition:  values of a and b have been exchanged
void swap(int& a, int& b);

// ---- main program ----

int main()
{
	const int size = 10;
	int nums[size];
	cout << "enter " << size << " numbers to sort:\n";
	for (int i = 0; i < size; i++)
		cin >> nums[i];
	selectionSort(nums, size);
	cout << "sorted numbers:\n";
	for (int i = 0; i < size; i++)
		cout << nums[i] << endl;
	return 0 ;
}

// ---- function definitions ----

void selectionSort(int a[], const int n)
{
	if (n > 1)
	{
		int j = findIndexOfLargest(a, n);
		if (j != (n-1))
			swap(a[j], a[n-1]);
		selectionSort(a, n-1);
	}
	return;
}

int findIndexOfLargest(const int a[], const int n)
{
	int indexOfLargest = 0;
	for (int j = 1; j < n; j++)
	{
		if (a[j] > a[indexOfLargest])
			indexOfLargest = j;
	}
	return indexOfLargest;
}

void swap(int& a, int& b)
{
	int temp = a;
	a = b;
	b = temp;
	return;
}