We know the output as follow:

• if n=1 output stone will be (0)
• if n=2 output stone will be (a, b)
• if n=3 output stone will be (2a, a+b, 2b)
• if n=4 output stone will be (3a, 2a+b, a+2b, 3b)
• if n=5 output stone will be (4a, 3a+b, 2a+2b, a+3b, 4b) final output can be formulated as (n-i-1)*a + i*b ***where i ranges from 0 to n-1* **

we can iterate over range 'n' and add these values to set remove duplicates.

def stones(n, a, b):
    # Write your code here
    st = set()
    for i in range(n):
        num = (n-i-1)*b + i*a
        st.add(num)

    return sorted(st)