Given a binary tree and a sum, determine if the tree has a root-to-leaf path such that adding up all the values along the path equals the given sum.

public class Solution {
    public boolean hasPathSum(TreeNode root, int sum) {
        if (root == null) {
            return false;
        }
        if (root.left == null && root.right == null) {
            return root.val == sum;
        } else {
            return hasPathSum(root.left, sum - root.val) || hasPathSum(root.right, sum - root.val);
        }
    }
}

class Solution(object):
    def hasPathSum(self, root, sum):
        """
        :type root: TreeNode
        :type sum: int
        :rtype: bool
        """

        if not root:
            return False

        if not root.left and not root.right:
            return root.val == sum

        return self.hasPathSum(root.left, sum - root.val) or self.hasPathSum(root.right, sum - root.val):