递归相关题目

/**
public class TreeNode {
    int val = 0;
    TreeNode left = null;
    TreeNode right = null;

    public TreeNode(int val) {
        this.val = val;

    }

}
*/ 
public class Solution {
    public void Mirror(TreeNode root) {
        if(root == null){
            return;
        }
        TreeNode subLeft = root.left;
        TreeNode subRight = root.right;
        root.left = subRight;
        root.right = subLeft;
        if(subLeft != null)
            Mirror(subLeft);
        if(subRight != null)
            Mirror(subRight);
        if(root.left == null || root.right == null){
            return;
        }      
       
    }
}