note pKai <p>It's no coincidence that stacks have a close relationship with trees.</p> <blockquote><i>You can get rid of any stacks whatsoever by keeping a parent pointer in the tree node data structure. </i></blockquote> <p>I wouldn't say you "get rid of any stacks" here.</p> <p>While you don't implement the stack as a list in classical ways, the list of "parent pointer(s)" between the root and the current node at any given moment of the traversal forms a stack.</p> <blockquote><i>While traversing, you need no memory other than the current and the previous node/state.</i></blockquote> <p>"previous node/state" obviously refers to the "top of stack", the single point where a stack is accessible.</p> 600456 600456