for dfsWithoutRecursion, when a node popped from the stack it should be checked that the current node is visited or not. Since stack has duplicated nodes, some nodes is visired doubly.
* CS-378 Find the Kth Smallest Element in the Union of Two Sorted Arrays
* CS-378 Fix name of unit test
* CS-378 Update merge algorithm to operate only on two input arrays
Co-authored-by: mikr <michael.krimgen@ximedes.com>