leetcode 222. Count Complete Tree Nodes

Given a complete binary tree, count the number of nodes.

Definition of a complete binary tree from Wikipedia:
In a complete binary tree every level, except possibly the last, is completely filled, and all nodes in the last level are as far left as possible. It can have between 1 and 2h nodes inclusive at the last level h.

class Solution {
public:
	int countNodes(TreeNode* root) {
		if (root == NULL)
			return 0;
		TreeNode*node = root;
		int k1(0), k2(0);
		while (node->left != NULL)
		{
			node = node->left; k1++;
		}
		node = root;
		while (node->right != NULL)
		{
			node = node->right; k2++;
		}
		if (k1 == k2)
			return pow(2, k1 + 1) - 1;
		
		return countNodes(root->left)+countNodes(root->right)+1 ;
	}
};

accept