Lintcode175-Revert Binary Tree-Easy

175. Invert Binary Tree

Invert a binary tree.

Example

Example 1:

Input: {1,3,#}
Output: {1,#,3}
Explanation:
	  1    1
	 /  =>  \
	3        3

Example 2:

Input: {1,2,3,#,#,4}
Output: {1,3,2,#,4}
Explanation: 

      1         1
     / \       / \
    2   3  => 3   2
       /       \
      4         4

Challenge

Do it in recursion is acceptable, can you do it without recursion?

 

递归法代码：

/**
 * Definition of TreeNode:
 * public class TreeNode {
 *     public int val;
 *     public TreeNode left, right;
 *     public TreeNode(int val) {
 *         this.val = val;
 *         this.left = this.right = null;
 *     }
 * }
 */

public class Solution {
    /**
     * @param root: a TreeNode, the root of the binary tree
     * @return: nothing
     */
    public void invertBinaryTree(TreeNode root) {
        if (root == null) {
            return;
        }

        TreeNode temp = root.right;
        root.right = root.left;
        root.left = temp;
        invertBinaryTree(root.left);
        invertBinaryTree(root.right);
    }
}