Given a binary tree, find the maximum path sum.
The path may start and end at any node in the tree.
For example: Given the below binary tree,
1
/
2 3
Return6.
1 /** 2 * Definition for binary tree 3 * struct TreeNode { 4 * int val; 5 * TreeNode *left; 6 * TreeNode *right; 7 * TreeNode(int x) : val(x), left(NULL), right(NULL) {} 8 * }; 9 */ 10 class Solution { 11 public: 12 int maxPathSum(TreeNode* root){ 13 int maxVal = INT_MIN; 14 maxPathSum(root,maxVal); 15 return maxVal; 16 } 17 int maxPathSum(TreeNode *root,int& maxVal) { 18 if(root == nullptr) return 0; 19 int leftRes = max(0,maxPathSum(root->left,maxVal)); 20 int rightRes = max(0,maxPathSum(root->right,maxVal)); 21 maxVal = max(maxVal,leftRes + rightRes + root->val); 22 return max(leftRes,rightRes) + root->val; 23 } 24 };