-
Notifications
You must be signed in to change notification settings - Fork 0
/
508. Most Frequent Subtree Sum.cpp
46 lines (38 loc) · 1.08 KB
/
508. Most Frequent Subtree Sum.cpp
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
// https://leetcode.com/problems/most-frequent-subtree-sum/
/**
* Definition for a binary tree node.
* struct TreeNode {
* int val;
* TreeNode *left;
* TreeNode *right;
* TreeNode() : val(0), left(nullptr), right(nullptr) {}
* TreeNode(int x) : val(x), left(nullptr), right(nullptr) {}
* TreeNode(int x, TreeNode *left, TreeNode *right) : val(x), left(left), right(right) {}
* };
*/
class Solution
{
int maxFreq = 0;
public:
vector<int> findFrequentTreeSum(TreeNode *root)
{
vector<int> result;
unordered_map<int, int> freq;
DFS(root, freq);
for (auto pair : freq)
if (pair.second == maxFreq)
result.push_back(pair.first);
return result;
}
int DFS(TreeNode *root, unordered_map<int, int> &freq)
{
if (root == nullptr)
return 0;
int left = DFS(root->left, freq);
int right = DFS(root->right, freq);
int sum = root->val + left + right;
freq[sum]++;
maxFreq = max(maxFreq, freq[sum]);
return sum;
}
};