checkSumInTree.java

    private static boolean checkSumInTree(TreeNode root, int k) {
        if (root != null)
            return checkSumInTreeAcum(root, k, 0);
        else
            return false;
    }

checkSumInTreeAcum.java

    private static boolean checkSumInTree(TreeNode node, int k, int acum) {
        if (node == null )
            return false;
        if (isLeaf(node) && acum + node.val == k)
            return true;
        else
            if (acum + node.val > k)
                return false;
            else
                return checkSumInTreeAcum(node.left, k, acum + node.val) || checkSumInTreeAcum(node.right, k, acum + node.val);
    }

isLeaf.java

    private static boolean isLeaf(TreeNode node) {
        return (node != null && node.right == null && node.left == null);
    }