public class isSymmetrical {

 public static void main(String[] args) {
 // 新建一棵二叉搜索樹
 TreeNode root=new TreeNode(10);
 TreeNode n1=new TreeNode(5);
 TreeNode n2=new TreeNode(5);
 TreeNode n3=new TreeNode(4);
 TreeNode n4=new TreeNode(7);
 TreeNode n5=new TreeNode(7);
 TreeNode n6=new TreeNode(4);
 //TreeNode n7=new TreeNode(19);
 root.left=n1;
 root.right=n2;
 n1.left=n3;
 n1.right=n4;
 n2.left=n5;
 n2.right=n6;
 //n6.right=n7;
 
 System.out.println("后序遍歷：");
 postOrderTraverse(root);
 
 boolean temp=symmetrical(root);
 System.out.println("\n"+"結果："+temp);
 }
 
 
 static boolean symmetrical(TreeNode pRoot)
  {
 if(pRoot == null){
      return true;
    }
    return comRoot(pRoot.left, pRoot.right);
  }
 
 
  static boolean comRoot(TreeNode left, TreeNode right) {
    if(left == null) 
     return right==null;
    if(right == null) 
     return false;
    if(left.val != right.val) 
     return false;
    return comRoot(left.right, right.left) && comRoot(left.left, right.right);
  }
  
  // 后序遍歷
  public static void postOrderTraverse(TreeNode node) { 
    if (node == null) 
      return; 
    postOrderTraverse(node.left); 
    postOrderTraverse(node.right); 
    System.out.print(node.val + " "); 
  }
}