Algorithm to find a duplicate entry in constant space and O(n) time

Question

Given an array of N integer such that only one integer is repeated. Find the repeated integer in O(n) time and constant space. There is no range for the value of integers or

Answer 1

We can do in linear time o(n) here as well

public class DuplicateInOnePass {

    public static  void duplicate()

   {
        int [] ar={6,7,8,8,7,9,9,10};
        Arrays.sort(ar);
        for (int i =0 ; i