TestClass

public class Calculator {
    public int add(int a, int b) {
        return a + b ;
    }

    public int min(int a, int b, int c) {
        if (a < b && a < c) {
            return a;
        } else if (b < c) {
            return b;
        }
        return c;
    }

    public String concat(String str1, String str2) {
        return str1 + str2;
    }

    public void bubbleSort(int[] arr) {
         int n = arr.length;
            for (int i = 0; i < n-1; i++) {
                for (int j = 0; j < n-i-1; j++) {
                    if (arr[j] > arr[j+1])
                    {
                        // swap arr[j+1] and arr[j]
                        int temp = arr[j];
                        arr[j] = arr[j+1];
                        arr[j+1] = temp;
                    }
                }
            }
    }
}