{"id":26868,"date":"2017-12-26T20:41:26","date_gmt":"2017-12-26T15:11:26","guid":{"rendered":"https:\/\/www.wikitechy.com\/technology\/?p=26868"},"modified":"2018-10-30T16:17:30","modified_gmt":"2018-10-30T10:47:30","slug":"python-algorithm-find-length-linked-list-iterative-recursive","status":"publish","type":"post","link":"https:\/\/www.wikitechy.com\/technology\/python-algorithm-find-length-linked-list-iterative-recursive\/","title":{"rendered":"Find Length of a Linked List both Iterative and Recursive"},"content":{"rendered":"

Find Length of a Linked List both Iterative and Recursive:<\/span><\/h3>\n

Write a Python function<\/a> to count number of nodes in a given singly linked list.<\/p>\n

\"C<\/p>\n

For example, the function should return 5 for linked list 1->3->1->2->1.<\/p>\n

Singly Linked List:<\/span><\/h3>\n

Singly Linked List is a collection of ordered set of elements<\/strong>. A Node in singly linked list has two parts \u2013 data part and link part<\/strong>. Data part of the node contains the actual information which is represented as node. Link part of the node contains address of next node linked to it.<\/p>\n

It can be traversed in only one direction because the node stores only next pointer. So, it can\u2019t\u00a0reverse linked list.<\/a><\/p>\n

Iterative Solution<\/strong><\/span><\/h3>\n
1) Initialize count as 0 \r\n2) Initialize a node pointer, current = head.\r\n3) Do following while current is not NULL\r\n     a) current = current -> next\r\n     b) count++;\r\n4) Return count<\/pre>\n
Python Programming:<\/strong><\/span><\/h3>\n
 
 <\/div> 
# A complete working Python program to find length of a# Linked List iteratively # Node classclass Node:    # Function to initialise the node object    def __init__(self, data):        self.data = data # Assign data        self.next = None # Initialize next as null  # Linked List class contains a Node objectclass LinkedList:     # Function to initialize head    def __init__(self):        self.head = None      # This function is in LinkedList class. It inserts    # a new node at the beginning of Linked List.    def push(self, new_data):         # 1 & 2: Allocate the Node &        #     Put in the data        new_node = Node(new_data)         # 3. Make next of new Node as head        new_node.next = self.head         # 4. Move the head to point to new Node        self.head = new_node      # This function counts number of nodes in Linked List    # iteratively, given 'node' as starting node.    def getCount(self):        temp = self.head # Initialise temp        count = 0 # Initialise count         # Loop while end of linked list is not reached        while (temp):            count += 1            temp = temp.next        return count  # Code execution starts hereif __name__=='__main__':    llist = LinkedList()    llist.push(1)    llist.push(3)    llist.push(1)    llist.push(2)    llist.push(1)    print 'Count of nodes is :',llist.getCount()<\/code><\/pre> <\/div>\n[ad type=”banner”]\n
Output:<\/strong><\/span><\/h3>\n
count of nodes is 5<\/pre>\n
Recursive Solution<\/strong><\/span><\/h3>\n
int getCount(head)<\/strong>\r\n1) If head is NULL, return 0.\r\n2) Else return 1 + getCount(head->next)<\/pre>\n
Python Programming:<\/strong><\/span><\/h3>\n
 
 <\/div> 
# A complete working Python program to find length of a# Linked List recursively # Node classclass Node:    # Function to initialise the node object    def __init__(self, data):        self.data = data  # Assign data        self.next = None  # Initialize next as null  # Linked List class contains a Node objectclass LinkedList:     # Function to initialize head    def __init__(self):        self.head = None      # This function is in LinkedList class. It inserts    # a new node at the beginning of Linked List.    def push(self, new_data):         # 1 & 2: Allocate the Node &        #        Put in the data        new_node = Node(new_data)         # 3. Make next of new Node as head        new_node.next = self.head         # 4. Move the head to point to new Node        self.head = new_node     # This function counts number of nodes in Linked List    # recursively, given 'node' as starting node.    def getCountRec(self, node):        if (not node): # Base case            return 0        else:            return 1 + self.getCountRec(node.next)     # A wrapper over getCountRec()    def getCount(self):       return self.getCountRec(self.head) # Code execution starts hereif __name__=='__main__':    llist = LinkedList()    llist.push(1)    llist.push(3)    llist.push(1)    llist.push(2)    llist.push(1)    print 'Count of nodes is :',llist.getCount()<\/code><\/pre> <\/div>\n[ad type=”banner”]\n
Output:<\/strong><\/span><\/h3>\n
count of nodes is 5<\/pre>\n","protected":false},"excerpt":{"rendered":"
Python Algorithm – Find Length of a Linked List both Iterative and Recursive – Linked List – Write a C function to count number of nodes in a given singly<\/p>\n","protected":false},"author":1,"featured_media":31259,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[79476,4148,79478],"tags":[72483,80240,80236,80239,80231,80237,80241,80232,80238,80235,80234,80230,80233],"class_list":["post-26868","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-linked-list","category-python","category-singly-linked-list","tag-c-linked-list","tag-find-length-of-linked-list-java","tag-geeksforgeeks","tag-get-length-of-linked-list-python","tag-how-to-calculate-the-length-of-linked-list-without-using-counter-in-java","tag-how-to-find-the-length-of-a-linked-list-python","tag-length-of-linked-list-c","tag-length-of-linked-list-python","tag-linked-list-implementation-in-python","tag-linkedlist-java","tag-recursive-linked-list-java","tag-size-of-linked-list-c","tag-what-is-a-class-loader-what-does-it-do"],"_links":{"self":[{"href":"https:\/\/www.wikitechy.com\/technology\/wp-json\/wp\/v2\/posts\/26868","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.wikitechy.com\/technology\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.wikitechy.com\/technology\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.wikitechy.com\/technology\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/www.wikitechy.com\/technology\/wp-json\/wp\/v2\/comments?post=26868"}],"version-history":[{"count":0,"href":"https:\/\/www.wikitechy.com\/technology\/wp-json\/wp\/v2\/posts\/26868\/revisions"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/www.wikitechy.com\/technology\/wp-json\/wp\/v2\/media\/31259"}],"wp:attachment":[{"href":"https:\/\/www.wikitechy.com\/technology\/wp-json\/wp\/v2\/media?parent=26868"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.wikitechy.com\/technology\/wp-json\/wp\/v2\/categories?post=26868"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.wikitechy.com\/technology\/wp-json\/wp\/v2\/tags?post=26868"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}