Question: 
Write a python function to find k number of operations required to make all elements equal.


Model's Code:
def min_Ops(arr, n, k):
    max_elem = max(arr)
    ops_needed = sum(max_elem - x for x in arr)
    
    if ops_needed % k != 0:
        return -1
    
    return ops_needed // k



Sample Correct Code:
def min_Ops(arr,n,k): 
    max1 = max(arr) 
    res = 0
    for i in range(0,n):  
        if ((max1 - arr[i]) % k != 0): 
            return -1 
        else: 
            res += (max1 - arr[i]) / k 
    return int(res) 


Asserts:
assert min_Ops([2,2,2,2],4,3) == 0
assert min_Ops([4,2,6,8],4,3) == -1
assert min_Ops([21,33,9,45,63],5,6) == 24


Tests:
Test 1 of 3: PASS
Test 2 of 3: FAIL: AssertionError()

Test 158 of 974: 114/158 (72.15189873417721%): failed