Create 234. Palindrome Linked List (#436)

Author: Chayandas07

234. Palindrome Linked List

@@ -0,0 +1,37 @@
+/**
+ * Definition for singly-linked list.
+ * struct ListNode {
+ *     int val;
+ *     ListNode *next;
+ *     ListNode() : val(0), next(nullptr) {}
+ *     ListNode(int x) : val(x), next(nullptr) {}
+ *     ListNode(int x, ListNode *next) : val(x), next(next) {}
+ * };
+ */
+class Solution {
+public:
+    bool isPalindrome(ListNode* head) {
+        ListNode* fast = head;
+        ListNode* slow = head;
+        ListNode* prev = NULL;
+
+        while(fast && fast -> next) {
+            ListNode* temp = slow -> next;
+            fast = fast -> next -> next;
+            slow -> next = prev;
+            prev = slow;
+            slow = temp;
+        }   
+        if(fast)
+            slow = slow -> next;
+        while(prev && slow) {
+            if(prev -> val != slow -> val)
+                return false;
+            
+            prev = prev -> next;
+            slow = slow -> next;
+        }
+
+        return true;
+    }
+};