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// 124. Binary Tree Maximum Path Sum
#include "leetcode.h"
/*
* a path in a binary tree is a sequence of nodes where each pair of adjacent
* nodes in the sequence has an edge connecting them. a node can only appear in
* the sequence at most once. note that the path does not need to pass through
* the root. the path sum of a path is the sum of the node's value in the path.
* given the 'root' of a binary tree, return the maximum path sum of any non
* empty path
*/
class Solution {
public:
int sum;
int maxPathSum(TreeNode *root) {
sum = INT_MIN;
solve(root);
return sum;
}
private:
int solve(TreeNode *root) {
if (!root)
return 0;
int left = max(0, solve(root->left));
int right = max(0, solve(root->right));
sum = max(sum, left + right + root->val);
return max(left, right) + root->val;
}
};
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