// SelectionSort.java
//
// CS 101  Class Example

import java.util.*; // for Random number generator

public class SelectionSort {
    
    // --------- Main program---------------------------------------------
  
    public static void main(String[] args) {
	int n = 10; // default array size
    
	if (args.length > 0) {		   // if provided,
	    n = Integer.parseInt(args[0]); // get array size from command line
	}
    
	int[] a = new int[n];
	initArr(a);		// initialize array with random numbers

	System.out.println();
	System.out.print("Initial array: ");
	printArr(a);
	selectionSort(a);
	System.out.print("Sorted array:  ");
	printArr(a);
    }
  
    // --------- Selection Sort ------------------------------------------

    public static int minIndexBetween(int[] a, int lo, int hi) {
	// Return the index of the minimum integer in a[lo..hi]
	int minValue = a[lo];
	int minIndex = lo;
	for (int i = lo+1; i <= hi; i++) {
	    if (a[i] < minValue) {
		minValue = a[i];
		minIndex = i;
	    }
	}
	return minIndex;
    }

    public static void selectionSort(int[] a) {
	// Selection sort - iterative version
	for (int i = 0; i < a.length-1; i++) {
	    int j = minIndexBetween(a, i, a.length-1);
	    if (i != j) {
		swap(a, i, j);
	    }
	}
    }

    public static void selectionSortRec(int[] a, int lo, int hi) {
	// Selection sort - recursive version
	if (lo < hi) {
	    int j = minIndexBetween(a, lo, hi);
	    swap(a, lo, j);
	    selectionSortRec(a, lo+1, hi);
	}
    }

    // --------- Helper Methods ------------------------------------------

    public static void swap(int[] a, int i, int j) {
	// Swap a[i] and a[j]
	int tmp = a[i];
	a[i] = a[j];
	a[j] = tmp;
    }

    public static void initArr(int[] a) {
	// initialize array a with random numbers between 0 and 99
	Random rand = new Random(); 
	for (int i = 0; i < a.length; i++) {
	    a[i] = Math.abs(rand.nextInt()) % 100;
	}
    }

    public static void printArr(int[] a) {
	// print array a
	for (int i=0; i < a.length; i++) {
	    System.out.print(a[i] + " "); // print all elements on same line
	}
	System.out.println(); // print newline
    }
  
}