Count Complete Tree Nodes

/*
Problem Statement: https://leetcode.com/problems/count-complete-tree-nodes/
*/

class Solution {
public:
	int countNodes(TreeNode* root) {
		if (!root)
			return 0;
		int l_cnt, r_cnt;
		TreeNode *l_node, *r_node;
		l_cnt = r_cnt = 0;
		l_node = r_node = root;

		while (l_node) {
			l_cnt++;
			l_node = l_node->left;
		}
		while (r_node) {
			r_cnt++;
			r_node = r_node->right;
		}

		if (l_cnt == r_cnt)
			return (1 << l_cnt) - 1;

		return 1 + countNodes(root->left) + countNodes(root->right);
	}
};