Create merge_two_lists.py that implements merging of two sorted linked lists

data_structures/linked_list/merge_two_lists.py

@@ -0,0 +1,103 @@
+"""
+Algorithm that merges two sorted linked lists into one sorted linked list.
+"""
+
+
+class Node:
+    def __init__(self, data):
+        self.data = data
+        self.next = None
+
+
+def create_linked_list(num_list: list) -> Node:
+    """
+    >>> node = create_linked_list([3,2,1])
+    >>> node.data
+    1
+    >>> node = create_linked_list([9,6,-3,5,8])
+    >>> node.data
+    -3
+    >>> create_linked_list([])
+
+    """
+    if not num_list:
+        return None
+
+    num_list.sort()
+    current = head = Node(num_list[0])
+    for i in range(1, len(num_list)):
+        current.next = Node(num_list[i])
+        current = current.next
+    return head
+
+
+def str_linked_list(head: Node) -> str:
+    """
+    >>> n1 = Node(1)
+    >>> n2 = Node(2)
+    >>> n3 = Node(3)
+    >>> n1.next = n2
+    >>> n2.next = n3
+    >>> str_linked_list(n1)
+    '1->2->3'
+    """
+    int_list = []
+    current = head
+    while current is not None:
+        int_list.append(f"{current.data}")
+        current = current.next
+    return "->".join(int_list)
+
+
+def merge_lists(list_one: list, list_two: list) -> Node:
+    """
+    >>> n1 = Node(1)
+    >>> n2 = Node(2)
+    >>> n3 = Node(3)
+    >>> n4 = Node(4)
+    >>> n5 = Node(5)
+    >>> n6 = Node(6)
+    >>> n1.next = n3
+    >>> n2.next = n4
+    >>> n4.next = n5
+    >>> n5.next = n6
+    >>> ll = merge_lists(n1, n2)
+    >>> str_linked_list(ll)
+    '1->2->3->4->5->6'
+    """
+    node_one = list_one
+    node_two = list_two
+    merged_list = current_node = Node(0)
+
+    while node_one is not None and node_two is not None:
+        if node_one.data <= node_two.data:
+            current_node.next = node_one
+            node_one = node_one.next
+        else:
+            current_node.next = node_two
+            node_two = node_two.next
+        current_node = current_node.next
+
+    if node_one is not None:
+        current_node.next = node_one
+
+    if node_two is not None:
+        current_node.next = node_two
+
+    return merged_list.next
+
+
+def main() -> None:
+    list1 = [3, 9, 7, 5, 1]
+    list2 = [4, 6, 5, 2, 8, 7, 10, 3, 0]
+    ll1 = create_linked_list(list1)
+    ll2 = create_linked_list(list2)
+    ll3 = merge_lists(ll1, ll2)
+    print(str_linked_list(ll3))
+
+
+if __name__ == "__main__":
+    main()
+    import doctest
+
+    doctest.testmod()