Write a function
class Solution { public int solution(int[] A); }
that, given a zero-indexed array A consisting of N integers, returns the number of distinct values in array A.
Assume that:
N is an integer within the range [0..100,000];
each element of array A is an integer within the range [−1,000,000..1,000,000].
For example, given array A consisting of six elements such that:
A[0] = 2    A[1] = 1    A[2] = 1
A[3] = 2    A[4] = 3    A[5] = 1
the function should return 3, because there are 3 distinct values appearing in array A, namely 1, 2 and 3.
Complexity:
expected worst-case time complexity is O(N*log(N));
expected worst-case space complexity is O(N), beyond input storage (not counting the storage required for input arguments).
Elements of input arrays can be modified.