leetcode

0 class Solution {

1 bool find(TreeNode *n, int val, string &path) const {

2 if (n->val == val) return true;

3

4 if (n->left && find(n->left, val, path))

5 path.push_back('L');

6 else if (n->right && find(n->right, val, path))

7 path.push_back('R');

8

9 return !path.empty();

10 }

11

12 public:

13 string getDirections(TreeNode *root, int startValue, int destValue) const {

14 string s, d;

15

16 find(root, startValue, s);

17 find(root, destValue, d);

18

19 while (!s.empty() && !d.empty() && s.back() == d.back())

20 s.pop_back(), d.pop_back();

21 return string(s.size(), 'U') + string(rbegin(d), rend(d));

22 }

23 };