标签：
Binary Search Tree Iterator
问题：
Implement an iterator over a binary search tree (BST). Your iterator will be initialized with the root node of a BST.
Calling next() will return the next smallest number in the BST.
Note: next() and hasNext() should run in average O(1) time and uses O(h) memory, where h is the height of the tree.
思路:
中序遍历的非递归算法实现 栈
我的代码：
public class BSTIterator { Stack<TreeNode> stack = new Stack<TreeNode>(); public BSTIterator(TreeNode root) { while(root != null) { stack.push(root); root = root.left; } } /** @return whether we have a next smallest number */ public boolean hasNext() { return !stack.isEmpty(); } /** @return the next smallest number */ public int next() { TreeNode top = stack.pop(); TreeNode right = top.right; if(right != null) { while(right != null) { stack.push(right); right = right.left; } } return top.val; } }
标签：
原文地址：http://www.cnblogs.com/sunshisonghit/p/4335834.html
