【題目敘述】https://leetcode.com/problems/binary-tree-maximum-path-sum/submissions/
/**
* 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 {
public:
int mx = INT_MIN;
int dfs(TreeNode* x){
if (!x) return 0;
int ret1 = dfs(x->left);
ret1 = max(0, ret1);
int ret2 = dfs(x->right);
ret2 = max(0, ret2);
mx = max(mx, x->val+ret1+ret2);
return x->val+max(ret1, ret2);
}
int maxPathSum(TreeNode* root) {
dfs(root);
return mx;
}
};