// CSE 143, Winter 2011, Marty Stepp
// This program performs some operations and
// measures and reports the total runtime.
// It forms a basis for runtime efficiency testing.

import java.util.*;

public class SpeedTest {
    public static void main(String[] args) {
        int[] a = createArray(10000000);
        
        // get start/stop system times to find out how fast the code ran
        long startTime = System.currentTimeMillis();
        
        // put code to time here...
        int r = range(a);
        
        long endTime = System.currentTimeMillis();
        long elapsed = endTime - startTime;
        System.out.println("Took " + elapsed + "ms");
    }
    
    // returns the range of values in the given array;
    // the difference between elements furthest apart
    // example: range({17, 29, 11, 4, 20, 8}) is 25
    public static int range(int[] numbers) {
        int maxDiff = 0;     // look at each pair of values
        for (int i = 0; i < numbers.length; i++) {
            for (int j = 0; j < numbers.length; j++) {
                int diff = Math.abs(numbers[j] - numbers[i]);
                if (diff > maxDiff) {
                    maxDiff = diff;
                }
            }
        }
        return maxDiff;
    }
    
    // Creates an array of the given length, fills it with random data,
    // and returns it.
    public static int[] createArray(int length) {
        int[] a = new int[length];
        Random rand = new Random();
        for (int i = 0; i < a.length; i++) {
            a[i] = rand.nextInt(1000000000);
        }
        return a;
    }
    
    // returns the range of values in the given array;
    // the difference between elements furthest apart
    // example: range({17, 29, 11, 4, 20, 8}) is 25
    public static int range2(int[] numbers) {
        int maxDiff = 0;     // look at each pair of values
        for (int i = 0; i < numbers.length; i++) {
            for (int j = i + 1; j < numbers.length; j++) {
                int diff = Math.abs(numbers[j] - numbers[i]);
                if (diff > maxDiff) {
                    maxDiff = diff;
                }
            }
        }
        return maxDiff;
    }
    
    // returns the range of values in the given array;
    // example: range({17, 29, 11, 4, 20, 8}) is 25
    public static int range3(int[] numbers) {
        int max = numbers[0]; // find max/min values
        int min = max;
        for (int i = 1; i < numbers.length; i++) {
            if (numbers[i] < min) {
                min = numbers[i];
            }
            if (numbers[i] > max) {
                max = numbers[i];
            }
        }
        return max - min;
    }
}