C#版 - 226. Invert Binary Tree(剑指offer 面试题19) - 题解

     4
   /   \
  2     7
 / \   / \
1   3 6   9

     4
   /   \
  7     2
 / \   / \
9   6 3   1

// Definition for a binary tree node.
//public class TreeNode
//{
//    public int val;
//    public TreeNode left;
//    public TreeNode right;
//    public TreeNode(int x) { val = x; }
//}
public class Solution
{
    public TreeNode InvertTree(TreeNode root)
    {
        if(root == null)
            return null;

        TreeNode p;
        p = root.left;                
        root.left = root.right;
        root.right = p;

        InvertTree(root.left);
        InvertTree(root.right);
        return root;
    }
}