The problem:
Given a binary tree, return the inorder traversal of its nodes‘ values.
For example:
Given binary tree {1,#,2,3},
1
2
/
3
return [1,3,2].
Note: Recursive solution is trivial, could you do it iteratively?
The recursion way is very trivial:
public class Solution { public List<Integer> inorderTraversal(TreeNode root) { ArrayList<Integer> ret = new ArrayList<Integer> (); if (root == null) return ret; helper(root, ret); return ret; } private void helper(TreeNode cur_root, ArrayList<Integer> ret) { if (cur_root == null) return; helper(cur_root.left, ret); ret.add(cur_root.val); helper(cur_root.right, ret); } }
[LeetCode#]Binary Tree Inorder Traversal
原文：http://www.cnblogs.com/airwindow/p/4216061.html