uploading new problem with its solution

Microsoft_Problems/Microsoft_Problem_12.py

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+"""
+This problem was asked by Microsoft.
+
+Let's represent an integer in a linked list format by having each node represent a digit in the number. The nodes make up the number in reversed order.
+
+For example, the following linked list:
+
+1 -> 2 -> 3 -> 4 -> 5
+
+is the number 54321.
+
+Given two linked lists in this format, return their sum in the same linked list format.
+
+For example, given
+
+9 -> 9
+
+5 -> 2
+
+return 124 (99 + 25) as:
+
+4 -> 2 -> 1
+
+"""
+
+
+class Node:
+    def __init__(self, val, next=None):
+        self.val = val
+        self.next = next
+
+
+def _linked_list_to_value(head):
+    if head is None:
+        return
+    value = ""
+    current = head
+    while current:
+        value += "".join(str(current.val))
+        current = current.next
+    return int(value[::-1])
+
+
+def _value_to_linked_list(value):
+    value = str(value)[::-1]
+    head = Node(value[0])
+    for i in range(len(value)):
+        if i == 0:
+            pass
+        else:
+            _append_node(head, value[i])
+    return head
+
+
+def _append_node(head, value):
+    current = head
+    while current:
+        if current.next is None:
+            current.next = Node(value)
+            break
+        current = current.next
+
+
+def display_linked_list(head):
+    if not head:
+        return
+    print(head.val)
+    display_linked_list(head.next)
+
+
+def two_sum(head, head2):
+    value = _linked_list_to_value(head) + _linked_list_to_value(head2)
+    return _value_to_linked_list(value)
+
+
+# Driver code
+linked_list_1 = Node(9, Node(9))
+linked_list_2 = Node(5, Node(2))
+display_linked_list(two_sum(linked_list_1, linked_list_2))