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.
The first line of input contains an integer T denoting the number of test cases. Then T test cases follow. Each test case contains an integer N which denotes the number of elements in the array. The second line of each test case contains n space separated integers denoting elements of the array a.
Print the duplicate elements from the given array. The order of the output should be in sorted order. Print -1 if no duplicate exists.
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.
1 <= T <= 100
1 <= N <= 105
0 <= A[i] <= N-1, for each valid i
0 3 1 2
2 3 1 2 3
Testcase 1: N=4 and all elements from 0 to (N-1 = 3) are present in the given array. Therefore output is -1.
Testcase 2: 2 and 3 occur more than once in the given array.
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