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Amazon Interview Question for Software Engineer/Developer (0 - 2 Years)

(3 posts)

1. 

   Name:
   guest
   Posted 4 months ago #
   
   

   Question 3 / 3
   You are given a function isListPalindrome which takes in a singly linked list of integers. Complete the function given, return 1 if the linked list is a palindrome, else return 0.
   Sample Test Cases:

   Input #00:
   1->2->1

   Output #00:
   1

   Explanation:
   The linked list when reversed still reads as 1->2->1. Hence it's a palindrome, return 1;

2. 

   kartik
   Moderator
   Posted 4 months ago #
   
   

   See http://www.geeksforgeeks.org/archives/1072

3. 

   Dedicated Programmer
   Member
   Posted 4 months ago #
   
   

   first reach the mid of the linked list through fast pointer slow pointer method,
   reverse the second half the linked list and take two pointers, one pointing to the head of the first part and another to the head of second part.
   increment both pointers if their data are same,repeat till we encounter Null.

   void ReverseLinkedList(struct node **start)
   {
   struct node *p=NULL,*q=*start,*r=NULL;
   while(q)
   {
   r=q->next;
   q->next=p;
   p=q;
   q=r;
   }
   *start=p;
   }

   int checkPalindrome(struct node *start)
   {
   struct node *fast=start,*slow=start;
   while(fast->next && fast->next->next)
   {
   fast=fast->next->next;
   slow=slow->next;
   }

   ReverseLinkedList(&(slow->next));
   fast=start;
   slow=slow->next;
   while(slow)
   {
   if(fast->data!=slow->data)
   return 0;
   fast=fast->next;
   slow=slow->next;
   }
   return 1;
   }

   correct me if mistaken.

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