leetcode

0 class Solution {

1 public:

2 int findSecondMinimumValue(TreeNode *root) {

3 if (!root) return -1;

4 int val = root->val;

5 long long res = LONG_MAX;

6 stack<TreeNode *> st;

7 st.push(root);

8 while (!st.empty()) {

9 TreeNode *root = st.top();

10 st.pop();

11 if (!root->left) continue;

12 int m = max(root->left->val, root->right->val);

13 if (m != val) res = min(res, (long long)m);

14 if (root->left->val == val) st.push(root->left);

15 if (root->right->val == val) st.push(root->right);

16 }

17

18 return res != LONG_MAX ? res : -1;

19 }

20 };