finished 2.5

Author: camilosalazar98

Python/chapter02/2.5 - Sum Lists/camilo_solution_2.5.py

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+"""
+Sum Lists: You have two numbers represented by a linked list, where each node
+contains a single digit.
+The digits are stored in reverse order, such that the 1 's digit is at the head
+of the list. Write a function that adds the two numbers and returns the sum as
+a linked list.
+
+EXAMPLE
+Input:(7-> 1 -> 6) + (5 -> 9 -> 2).That is,617 + 295. Output:2 -> 1 -> 9.That is,912.
+FOLLOW UP
+Suppose the digits are stored in forward order. Repeat the above problem. EXAMPLE
+lnput:(6 -> 1 -> 7) + (2 -> 9 -> 5).That is, 617 + 295. Output:9 -> 1 -> 2.Thatis,912.
+Hints: #7, #30, #71, #95, #109
+
+
+USE THIS IF YOUR SUPERDUPER STUCK
+https://www.youtube.com/watch?v=dm9drjU-DuM
+
+"""
+
+
+
+class Node:
+    #Singly link list
+    def __init__(self,data = None):
+        self.data = data
+        self.next = None
+
+class linklist:
+    #linkList class
+    def __init__(self):
+        self.head = None
+        self.size = 0
+
+    def push(self,data):
+        node = Node(data)# create a new node
+
+        if self.head == None: #check to see if the head node is empty
+            self.head = node # If its empty add it to the new node
+            self.size = 1
+            return
+        #if the head of the linklist is filled
+
+        current = self.head
+        while current.next is not None:#Check the current postion is empty
+        #Move to the next line if nothing is there
+            current = current.next
+
+
+        current.next = node #point self.head to a new node
+        self.size+=1
+
+    def lenght(self):
+        #note the count doesn't start at zero
+        cur = self.head
+        counter = 0
+        while cur is not None:
+            counter+=1
+            cur = cur.next
+        print('Linklist len: '+str(counter))
+        return counter
+
+    def printList(self):
+        curr = self.head
+        elem = []
+
+        while(curr != None):
+            elem.append(curr.data)
+            curr = curr.next
+        print(elem)
+    #1->2->3
+    def remove_node(self,data):
+        #1->2->3
+        curr = self.head
+        if curr is not None and curr.data == data:
+            self.head = curr.next
+            curr = None
+        #look for the node that has the data we are looking for
+        while curr is not None:
+            if curr.data == data:
+                break
+            prev = curr
+            curr = curr.next
+
+        #if data isn't found just reutrn
+        if(curr == None):
+            return
+
+        #allow us to unlink the nodes
+        prev.next = curr.next
+        curr = None
+
+
+    def sum_forward_backwards(self,llist_B):
+        if llist_B.head == None:
+            return "llist_B is None"
+
+        sum_list = linklist()
+        head_b = llist_B.head
+        curr = self.head #List A
+        carry = 0
+        while curr or head_b:
+            if curr == None and head_b == None:
+                i,j = 0
+            else:
+                i = curr.data
+                j = head_b.data
+
+            sum_ = i + j + carry
+            if sum_ >= 10:
+
+                carry = 1
+                r = sum_ % 10
+                sum_list.push(r)
+
+            else:
+                carry = 0
+                sum_list.push(sum_)
+            if curr:
+                curr = curr.next
+            if head_b:
+                head_b = head_b.next
+
+        self.head = sum_list.head
+
+
+
+
+
+link_A = linklist()
+link_B = linklist()
+link_A.push(7)
+link_A.push(1)
+link_A.push(6)
+
+link_B.push(5)
+link_B.push(9)
+link_B.push(2)
+link_A.sum_forward_backwards(link_B)
+link_A.printList()