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 must contain at least one node and does not need to go through the root.
For example:
Given the below binary tree,
1
/ \
2 3
Return 6.
参考
代码
/**
* Definition for a binary tree node.
* public class TreeNode {
* int val;
* TreeNode left;
* TreeNode right;
* TreeNode(int x) { val = x; }
* }
*/
class Solution {
private int res = Integer.MIN_VALUE;
public int maxPathSum(TreeNode root) {
helper(root);
return res;
}
public int helper(TreeNode root) {
if(root == null) return 0;
int left = Math.max(helper(root.left), 0);
int right = Math.max(helper(root.right), 0);
res = Math.max(res, left + right + root.val);
return Math.max(left, right) + root.val;
}
}
网友评论