Create Add_Two_Numbers

Author: printdhruv

Add_Two_Numbers

@@ -0,0 +1,88 @@
+"""
+   Programmer     : Dhruv Patel
+   Problem Name   : Add Two Numbers (LeetCode - Medium)
+   Problem          =>
+                       You are given two non-empty linked lists representing two non-negative integers.
+                       The digits are stored in reverse order, and each of their nodes contains a single digit.
+                       Add the two numbers and return the sum as a linked list.
+                       You may assume the two numbers do not contain any leading zero, except the number 0 itself.
+   Sample TestCases =>
+        Example 1:
+                  Input: l1 = [2,4,3], l2 = [5,6,4]
+                  Output: [7,0,8]
+                  Explanation: 342 + 465 = 807.
+        Example 2:
+                  Input: l1 = [0], l2 = [0]
+                  Output: [0]
+        Example 3:
+                  Input: l1 = [9,9,9,9,9,9,9], l2 = [9,9,9,9]
+                  Output: [8,9,9,9,0,0,0,1]
+
+  Thoughts =>         We have to travese the linkedlist l1 and l2 and sum elements from both list while traversing.
+                      while traversing carry will be generated if sum exceeds number 10 . we use carry while doing addition
+                      in next iteration if any are there and if not then simply append it. There might be a case where lenght of l1 is
+                      lesser then l2 or vice versa. in that case, we traverse remaining list.
+
+  Time - Complexity =>
+                        Worst    -  O(n) <- where n is representing largest list.
+  Space - Complexity =>
+                        Worst    -  Θ(n) <- where n is representing largest list.
+ """
+class ListNode:
+  def __init__(self, val=0, next=None):
+      self.val = val
+      self.next = next
+      
+class Solution:
+
+    def calculate(self,answer):
+        carry = answer // 10
+        answer = answer % 10
+        return carry,answer
+
+    def addTwoNumbers(self, l1: ListNode, l2: ListNode) -> ListNode:
+    
+        if not l2:
+            return l1
+        elif not l1:
+            return l2
+            
+        temp = None
+        carry = 0
+        
+        while l1 and l2:
+            answer = l1.val + l2.val + carry
+            carry = 0
+            if answer > 9:
+                carry,answer = self.calculate(answer)
+            if not temp:
+                temp = ListNode(answer)
+                head = temp
+            else:
+                temp.next = ListNode(answer)
+                temp = temp.next
+            l1 = l1.next
+            l2 = l2.next
+            
+        while l1:
+            answer = l1.val + carry
+            carry = 0
+            if answer > 9:
+                carry, answer = self.calculate(answer)
+            temp.next = ListNode(answer)
+            temp = temp.next
+            l1 = l1.next
+            
+        while l2:
+            answer = l2.val + carry
+            carry = 0
+            if answer > 9:
+                carry, answer = self.calculate(answer)
+            temp.next = ListNode(answer)
+            temp = temp.next
+            l2 = l2.next
+            
+        if carry > 0:
+            temp.next = ListNode(carry)
+            
+        return head