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44 | /**
* 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:
static constexpr int __MIN__ = -55665566;
int max3(int x0, int x1, int x2) {
return max(max(x0, x1), x2);
}
int max5(int x0, int x1, int x2, int x3, int x4) {
return max(max3(x0, x1, x2), max(x3, x4));
}
int dfs(TreeNode* node, int& ans) {
if (!node)
return __MIN__;
int left = dfs(node->left, ans);
int right = dfs(node->right, ans);
ans = max5(ans,
node->val,
node->val + left,
node->val + right,
node->val + left + right);
return max3(node->val,
node->val + left,
node->val + right);
}
public:
int maxPathSum(TreeNode* root) {
int ans = __MIN__;
dfs(root, ans);
return ans;
}
};
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