leetcode

0 class Solution {

1 public:

2 int sumOfLeftLeaves(TreeNode *root) {

3 if (!root) return 0;

4

5 int res = 0;

6 stack<TreeNode *> st;

7

8 st.push(root);

9 while (!st.empty()) {

10 TreeNode *root = st.top();

11 st.pop();

12 if (root->left) {

13 if (!root->left->left && !root->left->right)

14 res += root->left->val;

15 else

16 st.push(root->left);

17 }

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

19 }

20 return res;

21 }

22 };