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:
    bool isSymmetrical(TreeNode* pRoot) {
        if (pRoot == nullptr) return true;
        bool flag = true;
        function<void(TreeNode*, TreeNode*)> dfs = [&](TreeNode* l, TreeNode* r) {
            if (l == nullptr && r == nullptr) return;
            if (l == nullptr || r == nullptr) {
                flag = false;
                return;
            }
            if (l->val != r->val) {
                flag = false;
                return;
            }
            dfs(l->left,r->right);
            dfs(l->right,r->left);
        };
        dfs(pRoot->left,pRoot->right);
        return flag;
    }
};