Find repeated array

Problem: You have any array n+2. It has elements from 1 to n and two other elements are repeated. We need to find the repeated elements. Solution should not more then O(n) complexity

Hint: If you use the array value as the index to jum to some location. So the location where you are reaching after the jump should be visited only once. If you reach there more then one way, it means the key by which you are coming here already used.