offer-Two forks search tree and doubly linked list

Title: Enter a binary search tree to convert the two-fork search tree into a sorted doubly linked list. The space complexity is O (1).

The stupidest way to do this is to put the middle sequence traversal in an array or list and iterate through the concatenation again. But requires space complexity of O (1), there is no way to do so, this time can refer to this solution: http://blog.csdn.net/my_jobs/article/details/47666909 judge a tree is not a binary search tree, Can imitate the last method.

The subject is not the same as the solution of the book, feeling this slightly concise and good understanding, but are the model of the middle sequence traversal.

Private TreeNode pre = Null;private static TreeNode head = Null;public void convert (TreeNode root) {if (root = null) Retu Rn;convert (Root.left), if (pre! = null) {pre.right = Root;root.left = pre;} else {head = root;} Pre = Root;convert (root.right);}

The final head is the table header of the transformed list. Or that kind of summary, in the tree this data structure, many templates are can be applied, for example, did the above problem, the following one is easy to transform out. A comparison reveals that the code is really similar. Many of the tree's tool-like methods, such as the tree's hierarchical traversal, the height of the tree and so on, can be memorized, and then transformed.

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offer-Two forks search tree and doubly linked list