Leetcode-Day 65

Source: Internet
Author: User

Binary TreeQuestion 1Binary Tree Preorder Traversal Given A binary tree, return the preorder traversal of its nodes ' values.

For example:
Given binary Tree {1,#,2,3} ,

   1         2    /   3

Return [1,2,3] .

Note:recursive solution is trivial, could do it iteratively?

1 /**2 * Definition for a binary tree node.3 * public class TreeNode {4 * int val;5 * TreeNode left;6 * TreeNode right;7 * TreeNode (int x) {val = x;}8  * }9  */Ten  Public classSolution { Onelist<integer> result =NewArraylist<integer>(); A      PublicList<integer>preordertraversal (TreeNode root) { - PreorderTraversal2 (root); -         returnresult; the     } -      -      Public voidpreorderTraversal2 (TreeNode root) { -         if(Root = =NULL) +             return; - Result.add (root.val); + preordertraversal (root.left); A preordertraversal (root.right); at     } -}

Leetcode-Day 65

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