For an integer k rearrange all the elements of the given array in such way, that:
all elements that are less than k are placed before elements that are not less than k;
all elements that are less than k remain in the same order with respect to each other;
all elements that are not less than k remain in the same order with respect to each other.
For k = 6 and elements = [6, 4, 10, 10, 6], the output should be
splitByValue(k, elements) = [4, 6, 10, 10, 6].
For k = 5 and elements = [1, 3, 5, 7, 6, 4, 2], the output should be
splitByValue(k, elements) = [1, 3, 4, 2, 5, 7, 6].