Subarrays with distinct elements (Hackerblocks)

https://hack.codingblocks.com/contests/c/537/955

I couldn’t understand the solution on GFG.

I have derived a formula to calculate sum of length of subarray if all elements are different in the original array,
ie: n(n+1)(n+2)/6 , for eg n=3(distinct elements), ans=1.3 + 2.2 + 3.1=10, i have generalized it and derived the given formula.

I don’t know how to implement this if there are duplicates in the array. sliding window technique?

hey Tushar , pm me.
9873225242 Whatsapp Number.
-Anubhav Aron