bool _isSymmetric(TreeNode *root1, TreeNode *root2) { if (root1 == NULL || root2 == NULL) { return root1 == root2; } if (root1->val != root2->val) return false; return _isSymmetric(root1->left, root2->right) && _isSymmetric(root1->right, root2->left); }
bool _isSymmetric(TreeNode* l, TreeNode* r) { if (l == NULL && r == NULL) return true; if (l == NULL || r == NULL) return false; return l->val == r->val && _isSymmetric(l->left, r->right) && _isSymmetric(l->right, r->left); }
bool isSymmetric(TreeNode* root) { return _isSymmetric(root, root); }
bool isSymmetric(TreeNode *root) { if (root == NULL) return true; return _isSymmetric(root->left, root->right); }