请实现一个函数,用来判断一颗二叉树是不是对称的。注意,如果一个二叉树同此二叉树的镜像是同样的,定义其为对称的。
public class Test58 {
boolean isSymmetrical(TreeNode pRoot) {
if (pRoot == null) {
return true;
}
return isSymmetrical2(pRoot.left, pRoot.right);
}
private boolean isSymmetrical2(TreeNode left, TreeNode right) {
if (left == null && right == null) {
return true;
}
if ((left == null && right != null) || (right == null && left != null)) {
return false;
}
if (left.value != right.value) {
return false;
}
return isSymmetrical2(left.left, right.right) && isSymmetrical2(left.right, right.left);
}
}