leetcode

0 class Solution {

1 public:

2 int getMinimumDifference(TreeNode *root) {

3 stack<TreeNode *> st;

4 int res = INT_MAX;

5 TreeNode *prev = new TreeNode(INT_MAX);

6 while (true) {

7 while (root) {

8 st.push(root);

9 root = root->left;

10 }

11 if (st.empty()) break;

12 root = st.top();

13 st.pop();

14 res = min(res, abs(prev->val - root->val));

15 prev = root;

16 root = root->right;

17 }

18 return res;

19 }

20 };