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POArray Sorting Performance
 

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  1. POArray Sorting Performance
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    <p>This is a pretty simple, straightforward problem, but, of course, I've managed to do something wrong. First, I generated 5 different arrays of 10 random numbers--from 1 to 10, 1 to 100, up to 1 to 100,000. Then I took each array and performed 5 different types of sorts (for a total of 25), calculating the time it takes to perform the sorts. I cannot figure out why each and every result is 0ms regardless of the size of n. What am I doing wrong?</p> <pre><code>public class Lab16Sorting { public static void main(String[] args) { final int TOTAL_NUMBERS = 10; int count; int[] num = new int[TOTAL_NUMBERS]; Random rand = new Random(); // Generate 10 numbers from 1 - 10 System.out.println("SORT 10"); System.out.println("----------------"); for (count = 0; count &lt; TOTAL_NUMBERS; count++) num[count] = rand.nextInt(10); System.out.println("Array: " + num); runSort(num); // Generate 10 numbers from 1 - 100 System.out.println("\nSORT 100"); System.out.println("----------------"); for (count = 0; count &lt; TOTAL_NUMBERS; count++) num[count] = rand.nextInt(100); System.out.println("Array: " + num); runSort(num); // Generate 10 numbers from 1 - 1,000 System.out.println("\nSORT 1,000"); System.out.println("----------------"); for (count = 0; count &lt; TOTAL_NUMBERS; count++) num[count] = rand.nextInt(1000); System.out.println("Array: " + num); runSort(num); // Generate 10 numbers from 1 - 10,000 System.out.println("\nSORT 10,000"); System.out.println("----------------"); for (count = 0; count &lt; TOTAL_NUMBERS; count++) num[count] = rand.nextInt(10000); System.out.println("Array: " + num); runSort(num); // Generate 10 numbers from 1 - 100,000 System.out.println("\nSORT 100,000"); System.out.println("----------------"); for (count = 0; count &lt; TOTAL_NUMBERS; count++) num[count] = rand.nextInt(100000); System.out.println("Array: " + num); runSort(num); } /** * Run sort algorithms */ private static void runSort(int[] num) { long before; long after; // Run and display selection sort before = System.currentTimeMillis(); selectionSort(num); after = System.currentTimeMillis(); System.out.println("Selection sort took "+ (after-before) +" milliseconds"); // Run and display bubble sort before = System.currentTimeMillis(); bubbleSort(num); after = System.currentTimeMillis(); System.out.println("Bubble sort took "+ (after-before) +" milliseconds"); // Run and display insertion sort before = System.currentTimeMillis(); insertionSort(num); after = System.currentTimeMillis(); System.out.println("Insertion sort took "+ (after-before) +" milliseconds"); // Run and display merge sort before = System.currentTimeMillis(); mergeSort(num); after = System.currentTimeMillis(); System.out.println("Merge sort took "+ (after-before) +" milliseconds"); // Run and display quick sort before = System.currentTimeMillis(); quickSort(num); after = System.currentTimeMillis(); System.out.println("Quick sort took "+ (after-before) +" milliseconds"); } </code></pre> <p>I printed out the various array addresses and I see they're all the same (which makes sense since I'm using the same array object). I thought that was the problem and so I tried using different arrays (<code>int[] num</code>, <code>int[] num2</code>...) and I tried re-initializing the array after each <code>runSort()</code> method call with <code>num = new int[TOTAL_NUMBERS]</code>.</p>
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    1. USLuiggi Mendoza
    1. USspeedracer
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      1. VTDownMod
    1. COuse System.nanoTime() instead of System.currentTimeMillis()
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      1. USNYC Canuck
 

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