You are given a number of boxes, arr[i] = size of the box.
A smaller size of box fits into larger box. Return the number of boxes left.
**Condition:**
Small number box can be fitted into a larger number box only if space is available.
Ex : 3 3 4
Only one 2 can fit into 3, so arr end result is 2 3, so we are left with 2 boxes.

Tried : Binary search , Heaps  could not crack it, please help