Java for LeetCode 124 Binary Tree Maximum Path Sum

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

Return 6.

解题思路：

DFS暴力枚举，注意，如果采用static 全局变量的话，在IDE里面是可以通过，但在OJ上无法测试通过，因此需要建立一个类来储存结果，JAVA实现如下：

public class Solution {
	static public int maxPathSum(TreeNode root) {
		Result result=new Result(Integer.MIN_VALUE);
		dfs(root,result);
		return result.val;
	}
	static int dfs(TreeNode root,Result result) {
		if (root == null)
			return 0;
		int left_sum = Math.max(0, dfs(root.left,result));
		int right_sum = Math.max(0, dfs(root.right,result));
		result.val = Math.max(result.val, left_sum + right_sum + root.val);
		return Math.max(left_sum, right_sum) + root.val;
	}
}
class Result{
	int val;
	Result(){
		this.val=Integer.MIN_VALUE;
	}
	Result(int val){
		this.val=val;
	}
}