Method 1:(creating BST)
This can be done in O(nlogn) by inserting the elements(worst case:insert all n elements to find the 2 duplicates) into a BST and to check for duplicate elements.
Method 2:(creating count array)
Traverse the array once. While traversing, keep track of count of all elements in the array using a temp array count[] of size n, when you see an element whose count is already set, print it as duplicate.
Time complexity: O(n)
coding hangover 