How to tell if an array is a permutation in O(n)?

Question

Input: A read-only array of N elements containing integer values from 1 to N (some integer values can appear more than once!). And a memory zone of a fixed<

Answer 1

it looks like asking to find duplicate in array with stack machine.

it sounds impossible to know the full history of the stack , while you extract each number and have limited knowledge of the numbers that were taken out.