Given a binary tree, find the maximum path sum.
For this problem, a path is defined as any sequence of nodes from some starting node to any node in the tree along the parent-child connections. The path does not need to go through the root.
For example:
Given the below binary tree,
1
/ \
2 3
Return 6
.
/**
* Definition for a binary tree node.
* struct TreeNode {
* int val;
* TreeNode *left;
* TreeNode *right;
* TreeNode(int x) : val(x), left(NULL), right(NULL) {}
* };
*/
class Solution {
public:
int getMax(TreeNode* root, int &ans)
{
if(!root)
return ;
int leftMax = getMax(root->left, ans), rightMax = getMax(root->right, ans), Max = max(leftMax, rightMax);
int curMax = ((leftMax > ) ? leftMax : ) + ((rightMax > ) ? rightMax : ) + root->val;
if(curMax > ans)
ans = curMax;
if(Max <= )
return root->val;
return Max + root->val;
}
int maxPathSum(TreeNode* root) {
int ans = INT_MIN;
getMax(root, ans);
return ans;
}
};
分别求左右子树的最大节点和,若为负,则忽略,若为正,则加上本身的节点值。