198. Check if LL is palindrome or not

Given the head of a singly linked list representing a positive integer number. Each node of the linked list represents a digit of the number, with the 1st node containing the leftmost digit of the number and so on. Check whether the linked list values form a palindrome or not. Return true if it forms a palindrome, otherwise, return false.

A palindrome is a sequence that reads the same forward and backwards.

Example 1:

Input: head -> 3 -> 7 -> 5 -> 7 -> 3

Output: true

Explanation: 37573 is a palindrome.

Example 2:

Input: head -> 1 -> 1 -> 2 -> 1

Output: false

Explanation: 1121 is not a palindrome.

Now Your Turn!

Pick the correct output for the given input

Input: head -> 9 -> 9 -> 9 -> 9

Still unsure what the problem is asking ?

Let’s go through a few more examples, step by step, to make it clearer.

Constraints:

  • 1 <= number of nodes in the Linked List <= 105
  • 0 <= ListNode.val <= 9
  • The number represented does not contain any leading zeroes.

Hints

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Interview Follow-up Questions

0
/*
Definition of singly linked list:
struct ListNode
{
int val;
ListNode *next;
ListNode()
{
val = 0;
next = NULL;
}
ListNode(int data1)
{
val = data1;
next = NULL;
}
ListNode(int data1, ListNode *next1)
{
val = data1;
next = next1;
}
};
*/
 
class Solution {
public:
bool isPalindrome(ListNode* head) {
 
}
};
Test Case

Input:

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