1457. Pseudo-Palindromic Paths in a Binary Tree.cpp

class Solution {
public:
    int pseudoPalindromicPaths(TreeNode* root, int count = 0) {
        if (!root) return 0;
        count ^= 1 << (root->val - 1);
        int res = pseudoPalindromicPaths(root->left, count) + pseudoPalindromicPaths(root->right, count);
        if (root->left == root->right && (count & (count - 1)) == 0) res++;
        return res;
    }
};