leetcode

0 class Solution {

1 public:

2 bool isUnivalTree(TreeNode *root) {

3 if (!root) return true;

4 int val = root->val;

5 stack<TreeNode *> st;

6

7 st.push(root);

8 while (!st.empty()) {

9 TreeNode *root = st.top();

10 st.pop();

11 if (root->val != val) return false;

12 if (root->left) st.push(root->left);

13 if (root->right) st.push(root->right);

14 }

15

16 return true;

17 }

18 };