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31 | /**
* 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 {
private:
int ans;
int dfs(TreeNode *node) {
if (!node)
return 0;
int left = dfs(node->left);
int right = dfs(node->right);
ans = std::max(ans, left + right);
return std::max(left, right) + 1;
}
public:
int diameterOfBinaryTree(TreeNode *root) {
ans = 0;
dfs(root);
return ans;
}
};
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