Hi, first of all I'm new in this forum and I'm new at programming. My homework assignment is to use a Selection Sort algorithm and count how many basic operations it takes to sort 100, 1000, 10000, 100000 randomly generated elements. So I got that part of the code working as it creates files and sorts the elements. What I am having problems is with the counting of the fundamental operations. The Big O notation of Selection Sort is n^2. If I sort 100 then the number of fundamental operations should be 10000 or something close to it. Instead I get 16177. What exactly is considered a basic operation? +-*/, comparisons? Am I counting something that shouldn't be counting?

Code Java:

import java.util.*; import java.io.*; public class SelectionSortarray { static int counter = 0; public static void main(String a[]) throws IOException { int[] array = new int[100]; int[] array2 = new int[1000]; int[] array3 = new int[10000]; int[] array4 = new int[100000]; PrintWriter pw = new PrintWriter(new FileWriter("SS1.txt")); PrintWriter pw2 = new PrintWriter(new FileWriter("SS2.txt")); PrintWriter pw3 = new PrintWriter(new FileWriter("SS3.txt")); PrintWriter pw4 = new PrintWriter(new FileWriter("SS4.txt")); Random r = new Random(); for (int idx = 1; idx <= array.length; ++idx) // Will generate random numbers from 1 - 100 { int randomInt = r.nextInt(100); array[idx - 1] = randomInt; } selection_srt(array, array.length); System.out.println("Fundamental operations for 100 elements: " + counter); for(int in = 0; in < array.length; in++) { pw.println(array[in]); } pw.close(); for (int idx = 1; idx <= array2.length; ++idx) { int randomInt = r.nextInt(100); array2[idx - 1] = randomInt; } selection_srt(array2, array2.length); System.out.println("Fundamental operations for 1000 elements: " + counter); for(int in = 0; in < array2.length; in++) { pw2.println(array2[in]); } pw2.close(); for (int idx = 1; idx <= array3.length; ++idx) { int randomInt = r.nextInt(100); array3[idx - 1] = randomInt; } selection_srt(array3, array3.length); System.out.println("Fundamental operations for 10000 elements: " + counter); for(int in = 0; in < array3.length; in++) { pw3.println(array3[in]); } pw3.close(); for (int idx = 1; idx <= array4.length; ++idx) { int randomInt = r.nextInt(100); array4[idx - 1] = randomInt; } selection_srt(array4, array4.length); System.out.println("Fundamental operations for 100000 elements: " + counter); for(int in = 0; in < array4.length; in++) { pw4.println(array4[in]); } pw4.close(); } public static void selection_srt(int array[], int n){ counter += 3; // For x, x<n, x++ for(int x=0; x<n; x++){ int index_of_min = x; counter += 1; // for index_of_min for(int y=x; y<n; y++){ counter += 3; // y=x, y<n, y++ if(array[index_of_min]<array[y]){ index_of_min = y; counter += 2; // array<array[y] } } int temp = array[x]; counter += 1; // temp = array[x] array[x] = array[index_of_min]; counter += 1; // array[x] = array[index_of_min] array[index_of_min] = temp; counter += 1; // array[index_of_min] = temp } } }

It prints out to the screen this,

"Fundamental operations for 100 elements: 16177

Fundamental operations for 1000 elements: 1529746

Fundamental operations for 10000 elements: 151668395

Fundamental operations for 100000 elements: -2026816714"

Along with this can anyone tell me why I get a negative number with the last one? If anyone could help I would greatly appreciate it.