leetcode 日经贴，Cpp code -Count Complete Tree Nodes

Count Complete Tree Nodes

/**
 * Definition for a binary tree node.
 * struct TreeNode {
 *     int val;
 *     TreeNode *left;
 *     TreeNode *right;
 *     TreeNode(int x) : val(x), left(NULL), right(NULL) {}
 * };
 */
class Solution {
public:
    int countHeight(TreeNode *r, bool le) {
        if (!r) return 0;
        if (le) {
            return countHeight(r->left, le) + 1;
        } else {
            return countHeight(r->right, le) + 1;
        }
    }
    bool checkNode(TreeNode *r, int s, int h) {
        if (h < 0) return r? true:false;
        if (!r) return false;
        if (s & (1 << h)) {
            return checkNode(r->right, s, h - 1);
        } else {
            return checkNode(r->left, s, h - 1);
        }
    }
    int countNodes(TreeNode* root) {
        int hl = countHeight(root, true);
        int hr = countHeight(root, false);
        if (hl == hr) {
            return (1 << hl) - 1;
        }
        int low = 0, high = (1<<hr) - 1, mid;
        while (low < high) {
            mid = (low + high) / 2;
            if (checkNode(root, mid, hr - 1)) {
                low = mid + 1;
            } else {
                high = mid;
            }
        }
        return (1 << hr) - 1 + low;
    }
};