Leecode brush title
- Title Description
Given a non-null binary tree, and return the maximum path.
In this problem, it is defined as a path from any node in the tree, to the sequence of any node. The path includes at least one node, and not necessarily through the root node.
-
Example
Input: [1,2,3]1 / \ 2 3
Output: 6
- Code
/*最大值只有四种情况:节点, 节点及左树,节点及右树,左右树及节点。最后一种情况不能作为左右树继续递归,需要保存临时最大值*/
/**
* 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 maxPathSum(TreeNode* root) {
if(root == NULL)
return 0;
int ans = INT_MIN;
MaxSum(root,ans);
return ans;
}
int MaxSum(TreeNode* root, int& ans)
{
if(root == NULL)
return 0;
int left = max(0,MaxSum(root->left,ans));
int right = max(0,MaxSum(root->right,ans));
ans = max(ans, left+right+root->val);
return max(left+root->val,right+root->val);
}
};