array sort speed.java

import java.util.Arrays;
import java.util.Random;
import java.util.Scanner;

public class Main {
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        System.out.print("Enter the size of the array to sort: ");
        int size = sc.nextInt();
        sc.close();

        int[] arr = new int[size];
        Random rand = new Random();
        for (int i = 0; i < size; i++) {
            arr[i] = rand.nextInt(10000);
        }

        long startTime = System.currentTimeMillis();
        Arrays.sort(arr);
        long endTime = System.currentTimeMillis();
        long elapsedTime = endTime - startTime;

        System.out.println("Sorted " + size + " elements in " + elapsedTime + " ms");
    }
}
//There is a direct relation between the size of the array and time it takes to sort it.
//test 1:
Enter the size of the array to sort: 100000
Sorted 100000 elements in 17 ms

//test 2:
Enter the size of the array to sort: 99
Sorted 99 elements in 0 ms

//test 3: 
Enter the size of the array to sort: 10000
Sorted 10000 elements in 2 ms

//O(n log n) -------- from the internet(it is hard to find it manually until now).
//question: 10000 took 2 ms , then how much time will 100000 take?
answer: 1000 log 1000 ========== 2 ms
        100000 log 100000 ====== X ms , find X...
    (1000 log 1000) * X = 200000 log 100000
    X = 200 (log (100000) / log (1000))
    X = 200 (5/3)
    X = 333
    well, it is not 17 ms cause the running time is dependent on many external factors.