Sum of deepest leaves

/**
Given a binary tree, return the sum of values of its deepest leaves
 * Definition for a binary tree node.

 * public class TreeNode {
 *     int val;
 *     TreeNode left;
 *     TreeNode right;
 *     TreeNode(int x) { val = x; }
 * }
 */
class Solution {
    private static int sum, maxPathCount;
    public int deepestLeavesSum(TreeNode root) {
        sum = 0;
        if(root == null){
            return sum;
        }
        maxPathCount = 0;
        int currPathCount = 0;
        traverse(currPathCount,root);
        return sum;
    }
    private void traverse(int currPathCount,TreeNode currNode){
        if(currNode.left == null && currNode.right == null){
            currPathCount++;
            if(maxPathCount < currPathCount){
                maxPathCount = currPathCount;
                sum = currNode.val;
            }else if(maxPathCount == currPathCount){
                sum += currNode.val;
            }
        }else{
            currPathCount++;
            if(currNode.left != null){
                traverse(currPathCount, currNode.left);
            }
            if(currNode.right != null){
                traverse(currPathCount, currNode.right);
            }
            return;
        }
        return;
    }
}