Leetcode 437 跑不通这条测试用例
以下是我的代码：

class Solution {
    public int pathSum(TreeNode root, int targetSum) {
        if (root == null) return 0;
        int res = 0;
        res += findPath(root, targetSum);
        return res + pathSum(root.left, targetSum) + pathSum(root.right, targetSum);
    }
    private int findPath(TreeNode node, int num) {
        if (node == null) return 0;
        int res = 0;
        if (node.val == num) res += 1;
        return res + findPath(node.left, num - node.val) + findPath(node.right, num - node.val);
    }
}

但是在跑这条测试用例时出现了wrong answer

root =
[1000000000,1000000000,null,294967296,null,1000000000,null,1000000000,null,1000000000]，
targetSum =
0

是不是因为int型数值溢出了呢？可以把findPath的输入改成long型吗？