Geeksforgeeks

Error

Given an array a[] of size N which contains elements from 0 to N-1, you need to find all the elements occurring more than once in the given array.

**Example 1:**

**Input:
**N = 4
a[] = {0,3,1,2}
**Output: **-1**
Explanation: **N=4 and all elements from 0
to (N-1 = 3) are present in the given
array. Therefore output is -1.

**Example 2:**

**Input:
**N = 5
a[] = {2,3,1,2,3}
**Output: **2 3 **
Explanation: **2 and 3 occur more than once
in the given array.

**Your Task:**

Complete the function **duplicates()** which takes array a[] and n as input as parameters and returns a list of elements that occur more than once in the given array in sorted manner. If no such element is found return -1.

**Expected Time Complexity:** O(n).

**Expected Auxiliary Space:** O(n).

Note : The extra space is only for the array to be returned.

Try and perform all operation withing the provided array.

**Constraints:**

1 <= N <= 10^{5}

0 <= A[i] <= N-1, for each valid i

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Find duplicates in an array

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