Palindrome Linked List - Amazon Top Interview Questions
Problem Statement :
Given a singly linked list node whose values are integers, determine whether the linked list forms a palindrome. Constraints n ≤ 100,000 where n is the length of node Example 1 Input node = [5, 3, 5] Output True Explanation 5 -> 3 -> 5 is a palindrome. Example 2 Input node = [12, 8, 12] Output True Explanation The values of the linked list are the same forwards and backwards.
Solution :
Solution in C++ :
bool checkPalindrome(LLNode *node, LLNode **curr) {
if (node == NULL) return true;
bool check = checkPalindrome(node->next, curr);
if (node->val != (*curr)->val) return false;
*curr = (*curr)->next;
return check;
}
bool solve(LLNode *node) {
LLNode *curr = node;
return checkPalindrome(node, &curr);
}
Solution in Python :
class Solution:
def solve(self, node):
fast, slow = node, node
while fast and fast.next:
fast = fast.next.next
slow = slow.next
right = None
while slow:
p = slow.next
slow.next = right
right = slow
slow = p
left = node
while left is not None and right is not None:
if left.val != right.val:
return False
left = left.next
right = right.next
return True
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