使用迭代方法:
public boolean isSymmetric(TreeNode root) {
if(root==null){
return true;
}
if(root!=null){
return leftAndRightTreeNode(root.left,root.right);
}
return true;
}
public boolean leftAndRightTreeNode(TreeNode left,TreeNode right){
if(left==null && right==null){
return true;
}
if(left==null && right!=null){
return false;
}
if(left!=null && right==null){
return false;
}
if(left!=null && right!=null){
if(left.val==right.val){
return leftAndRightTreeNode(left.left,right.right)&& leftAndRightTreeNode(left.right,right.left);
}
}
return false;
}