题解 | #对称的二叉树#

/**
 * struct TreeNode {
 *  int val;
 *  struct TreeNode *left;
 *  struct TreeNode *right;
 *  TreeNode(int x) : val(x), left(nullptr), right(nullptr) {}
 * };
 */
class Solution {
  public:
    /**
     * 代码中的类名、方法名、参数名已经指定，请勿修改，直接返回方法规定的值即可
     *
     *
     * @param pRoot TreeNode类
     * @return bool布尔型
     */
    bool traversal(TreeNode* left, TreeNode* right) {
        if (right == NULL && left == NULL) return true;
        if (right != NULL && left == NULL) return false;
        if (right == NULL && left != NULL) return false;
        if (left->val != right->val) return false;
        return traversal(left->left, right->right) &&
               traversal(left->right, right->left);

    }
    bool isSymmetrical(TreeNode* pRoot) {
        // write code here
        if (!pRoot) return true;
        return traversal(pRoot->left, pRoot->right);
    }
};