二叉树的镜像

 class TreeNode {
    int val = 0;
    TreeNode left = null;
    TreeNode right = null;

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

    }

}

public class Solution {

        //方法二:精简递归方法
      public void Mirror2(TreeNode root) {
        TreeNode tmp = null;
        if (root != null)
            {
            tmp = root.left;
            root.left = root.right;
            root.right = tmp;
            if (root.left != null)
                Mirror2(root.left);
            if (root.right != null)
                Mirror2(root.right);
        }
    }

       //方法一:一般递归方法
    public void Mirror(TreeNode root) {
        if(root==null||(root.left==null&&root.right==null))
        {
            return;
        }
       Switch(root);

    }
    public void Switch(TreeNode root){

        if(root.left!=null&&root.right!=null){

          TreeNode temp=root.left;
          root.left=root.right;
          root.right=temp;
        }else if(root.left==null)
        {
            root.left=root.right;
            root.right=null;

        }else if(root.right==null)
        {
            root.right=root.left;
            root.left=null;
        }else{
            return;
        }
        if(root.left!=null)
        {
             Switch(root.left);
        }

        if(root.right!=null)
        {
            Switch(root.right);
        }

    }
    //二叉树的中序遍历
    public void inOrder(TreeNode head){

         if(head!=null){
             inOrder(head.left);
             visit(head);
             inOrder(head.right);
         }
    }
    public void visit(TreeNode node){

         System.out.print(node.val+" ");
    }
    public static void main(String[]args){
       // System.out.println("Hello");
        Solution s=new Solution();
        TreeNode head=new TreeNode(8);
        head.left=new TreeNode(6);
        head.right=new TreeNode(10);
        head.left.left=new TreeNode(5);
        head.left.right=new TreeNode(7);
        head.right.left=new TreeNode(9);
        head.right.right=new TreeNode(11);

        TreeNode head2=new TreeNode(8);
        head2.left=new TreeNode(7);
        head2.left.left=new TreeNode(6);
        head2.left.left.left=new TreeNode(5);
        head2.left.left.left.left=new TreeNode(4);

        s.inOrder(head2);
        System.out.println();
        s.Mirror(head2);
        s.inOrder(head2);

    }
}