C17/CSFunA/Huma Hameed

linked_lists/intersection.py

@@ -6,9 +6,43 @@ def __init__(self, value):
         self.val = value
         self.next = None
 
+def len_check(head):
+    head_len = 0
+
+    while head:
+        head_len += 1
+        head = head.next
+
+    return head_len
+
 
 def intersection_node(headA, headB):
     """ Will return the node at which the two lists intersect.
         If the two linked lists have no intersection at all, return None.
     """
-    pass
+    if not headA or not headB:
+        return None
+
+    headA_len = len_check(headA)
+    headB_len = len_check(headB)
+
+    if headA_len > headB_len:
+        move = headA_len - headB_len
+        while move:
+            headA = headA.next
+            move -= 1
+    elif headB_len > headA_len:
+        move = headB_len - headA_len
+        while move:
+            headB = headB.next
+            move -= 1
+
+    while headA:
+        if headA != headB:
+            headA = headA.next
+            headB = headB.next
+        elif headA == headB:
+            node_intersection = headA
+            return node_intersection
+
+    return None