题解 | #对称的二叉树#

/*
struct TreeNode {
    int val;
    struct TreeNode *left;
    struct TreeNode *right;
    TreeNode(int x) :
            val(x), left(NULL), right(NULL) {
    }
};
*/
class Solution {
public:
    bool isEqualNode(TreeNode* pLeft, TreeNode* pRight) {
        if (pLeft == nullptr && pRight == nullptr) return true;
        if (pLeft == nullptr || pRight == nullptr) return false;

        if (pLeft->val != pRight->val) return false;

        return isEqualNode(pLeft->left, pRight->right) && 
               isEqualNode(pLeft->right, pRight->left);
    }

    bool isSymmetrical(TreeNode* pRoot) {
        if (pRoot == nullptr) return true;

        return isEqualNode(pRoot->left, pRoot->right);
    }

};