题解 | #对称的二叉树#

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

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

    }

}
*/
public class Solution {
    boolean isSymmetrical(TreeNode pRoot) {
        if(pRoot == null) {
            return true;
        }
        return isSymmetrical(pRoot.left, pRoot.right);
    }
    boolean isSymmetrical(TreeNode l, TreeNode r) {
        if(l == null) {
            return r == null;
        }
        if(r == null) {
            return l == null;
        }
        
        return l.val == r.val && 
            isSymmetrical(l.left, r.right) && 
            isSymmetrical(l.right, r.left);
    }
}