Adding Efficient Solution for Problem - 876 - Middle LinkedList

Author: Vanditg

Middle_LinkedList/EfficientSolution.py

@@ -0,0 +1,64 @@
+##==================================
+## Leetcode
+## Student: Vandit Jyotindra Gajjar
+## Year: 2020
+## Problem: 876
+## Problem Name: Middle of the Linked List 
+##===================================
+#
+#Given a non-empty, singly linked list with head node head, return a middle node of linked list.
+#
+#If there are two middle nodes, return the second middle node.
+#
+#Example 1:
+#
+#Input: [1,2,3,4,5]
+#Output: Node 3 from this list (Serialization: [3,4,5])
+#The returned node has value 3.  (The judge's serialization of this node is [3,4,5]).
+#Note that we returned a ListNode object ans, such that:
+#ans.val = 3, ans.next.val = 4, ans.next.next.val = 5, and ans.next.next.next = NULL.
+#
+#Example 2:
+#
+#Input: [1,2,3,4,5,6]
+#Output: Node 4 from this list (Serialization: [4,5,6])
+#Since the list has two middle nodes with values 3 and 4, we return the second one.
+class Solution:
+    def middleNode(self, head):
+        tmp = head    #Referencing head value to tmp
+		counter = 0   #Initialize counter
+		while tmp:    #While our head is not empty
+            counter += 1    #We'll traverse through list and increase our counter by 1.
+            tmp = tmp.next   #We'll point to next value
+        middle = counter // 2    #Find the middle index of linked list, that return integer value
+        newTmp = head    #Referencing head value to newTmp
+        for i in range(middle):    #Loop throuh middle in list
+            newTmp = newTmp.next   #We'll point till we reach middle index
+        return newTmp    #We'll return the newTmp value or serialization. 
+#Example:
+#tmp = [1, 2, 3, 4, 5, 6]
+#counter = 0
+#While Loop
+#tmp = [1, 2, 3, 4, 5, 6]
+#counter = 1
+#tmp = [2, 3, 4, 5, 6]
+#counter = 2
+#tmp = [3, 4, 5, 6]
+#counter = 3
+#tmp = [4, 5, 6]
+#counter = 4
+#tmp = [5, 6]
+#counter = 5
+#tmp = [6]
+#counter = 6
+#Loop terminates
+#Middle = counter // 2 ===>>> 3
+#newTmp = [1, 2, 3, 4, 5, 6]
+#For loop 
+#i = 0
+#newTmp = [2, 3, 4, 5, 6]
+#i = 1
+#newTmp = [3, 4, 5, 6]
+#i = 2
+#newTmp = [4, 5, 6]
+#This newTmp we'll return as we reached the middle.