LeetCode 124 Binary Tree Maximum Path Sum

public class Solution {
	static int max = Integer.MIN_VALUE;

	public int maxPathSum(TreeNode root) {
		max = Integer.MIN_VALUE;
		PathSum(root);
		return max;
	}

	public int PathSum(TreeNode root) {
		if(root==null) return 0;
		int leftmaxsum=0;
		int rightmaxsum=0;
		int temp=root.val;
        if(root.left!=null){
        	leftmaxsum=Math.max(PathSum(root.left),0);
        } 
        if(root.right!=null){
        	rightmaxsum=Math.max(PathSum(root.right),0);
        }
        temp=root.val+leftmaxsum+rightmaxsum;
        max=max>temp?max:temp;
        return Math.max(root.val,Math.max(root.val+leftmaxsum, root.val+rightmaxsum));
    }
}