data_structures/linked_list: Add __len__() function and tests

data_structures/linked_list/__init__.py

@@ -2,21 +2,24 @@ class Node:
     def __init__(self, item, next):
         self.item = item
         self.next = next
-
 class LinkedList:
     def __init__(self):
         self.head = None
+        self.size=0
 
     def add(self, item):
         self.head = Node(item, self.head)
+        self.size+=1
 
     def remove(self):
         if self.is_empty():
             return None
         else:
             item = self.head.item
             self.head = self.head.next
+            self.size-=1
             return item
-
     def is_empty(self):
         return self.head is None
+    def __len__(self): #add python predefined len function
+        return self.size

data_structures/linked_list/doubly_linked_list.py

@@ -11,6 +11,7 @@ class LinkedList:           #making main class named linked list
     def __init__(self):
         self.head = None
         self.tail = None
+        self.size=0
 
     def insertHead(self, x):
         newLink = Link(x)                            #Create a new link with a value attached to it
@@ -20,13 +21,15 @@ def insertHead(self, x):
             self.head.previous = newLink             # newLink <-- currenthead(head)
         newLink.next = self.head                     # newLink <--> currenthead(head)
         self.head = newLink                          # newLink(head) <--> oldhead
+        self.size+=1
 
     def deleteHead(self):
         temp = self.head
         self.head = self.head.next                   # oldHead <--> 2ndElement(head) 
         self.head.previous = None                    # oldHead --> 2ndElement(head) nothing pointing at it so the old head will be removed
         if(self.head is None):
             self.tail = None                         #if empty linked list
+        self.size-=1
         return temp
 
     def insertTail(self, x):
@@ -35,11 +38,13 @@ def insertTail(self, x):
         self.tail.next = newLink                    # currentTail(tail) --> newLink -->
         newLink.previous = self.tail                #currentTail(tail) <--> newLink -->
         self.tail = newLink                         # oldTail <--> newLink(tail) -->
+        self.size+=1
 
     def deleteTail(self):
         temp = self.tail
         self.tail = self.tail.previous              # 2ndLast(tail) <--> oldTail --> None
         self.tail.next = None                       # 2ndlast(tail) --> None
+        self.size-=1
         return temp
 
     def delete(self, x):
@@ -57,7 +62,7 @@ def delete(self, x):
         else: #Before: 1 <--> 2(current) <--> 3
             current.previous.next = current.next # 1 --> 3
             current.next.previous = current.previous # 1 <--> 3
-
+       self.size-=1
     def isEmpty(self):                               #Will return True if the list is empty
         return(self.head is None)
 
@@ -67,7 +72,8 @@ def display(self):                                #Prints contents of the list
             current.displayLink()
             current = current.next  
         print()
-
+    def __len__(self):
+        return self.size
 class Link:
     next = None                                       #This points to the link in front of the new link
     previous = None                                   #This points to the link behind the new link

maths/prime_check.py

@@ -22,8 +22,9 @@ def prime_check(number):
 
     # Except 2, all primes are odd. If any odd value divide
     # the number, then that number is not prime.
-    odd_numbers = range(3, int(math.sqrt(number)) + 1, 2)
-    return not any(number % i == 0 for i in odd_numbers)
+    # prime number all are in 6k+1 or 6k-1 form where k belongs to integers so i have modified range(5,root(n),6)
+    special_number=range(5,int(math.sqrt(number)),6)
+    return not any((number % i == 0 or number%(i+2)==0) for i in special_number)
 
 
 class Test(unittest.TestCase):