leetcode

0 class Solution {

1 public:

2 vector<int> findFrequentTreeSum(TreeNode *root) {

3 unordered_map<int, int> um;

4 stack<TreeNode *> st({root});

5 while (!st.empty()) {

6 TreeNode *root = st.top();

7 if (root) {

8 st.push(nullptr);

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

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

11 continue;

12 }

13 st.pop();

14 root = st.top();

15 st.pop();

16 if (root->left) root->val += root->left->val;

17 if (root->right) root->val += root->right->val;

18 um[root->val]++;

19 }

20

21 vector<int> res;

22 int maxi = 0;

23 for (const auto [k, v] : um) {

24 if (v < maxi) continue;

25 if (v == maxi)

26 res.push_back(k);

27 else {

28 maxi = v;

29 res = {k};

30 }

31 }

32 return res;

33 }

34 };