Traversal

To traverse a data structure for example #tree or #graph, one could use several methods:

• pre-order: traversal performed on a node before its children
• post-order: traversal performed on a node after its children
• in-order: traversal performed from the left to the node then to the right
• level-order: traversal performed on one depth to deeper depth

Analysis

• This operation will result in \(O(N)\)

Attention

• NULL case should be handled first
• In level-order traversal, do not use recursive method, use it alongside with Queue instead