Check if a linked list of strings forms a palindrome
Given a linked list handling string data, check to see whether data is palindrome or not?
For example,
Input : a -> bc -> d -> dcb -> a -> NULL Output : True String "abcddcba" is palindrome. Output : a -> bc -> d -> ba -> NULL Output : False String "abcdba" is not palindrome.
The idea is very simple. Construct a string out of given linked list and check if the constructed string is palindrome or not.
C/C++
// Program to check if a given linked list of strings// form a palindrome#include <bits/stdc++.h>using namespace std; /* Link list node */struct Node{ string data; Node* next;}; // A utility function to check if str is palindrome// or notbool isPalindromeUtil(string str){ int length = str.length(); // Match characters from beginning and // end. for (int i=0; i<length/2; i++) if (str[i] != str[length-i-1]) return false; return true;} // Returns true if string formed by linked// list is palindromebool isPalindrome(Node *node){ // Append all nodes to form a string string str = ""; while (node != NULL) { str.append(node->data); node = node->next; } // Check if the formed string is palindrome return isPalindromeUtil(str);} // A utility function to print a given linked listvoid printList(Node *node){ while (node != NULL) { cout << node->data << " -> "; node = node->next; } printf("NULL\n");} /* Function to create a new node with given data */Node *newNode(const char *str){ Node *new_node = new Node; new_node->data = str; new_node->next = NULL; return new_node;} /* Driver program to test above function*/int main(){ Node *head = newNode("a"); head->next = newNode("bc"); head->next->next = newNode("d"); head->next->next->next = newNode("dcb"); head->next->next->next->next = newNode("a"); isPalindrome(head)? printf("true\n"): printf("false\n"); return 0;} |
Java
// Java Program to check if a given linked list of strings// form a palindrome import java.util.Scanner; // Linked List nodeclass Node{ String data; Node next; Node(String d) { data = d; next = null; }} class LinkedList_Palindrome{ Node head; // A utility function to check if str is palindrome // or not boolean isPalidromeUtil(String str) { int length = str.length(); // Match characters from beginning and // end. for (int i=0; i<length/2; i++) if (str.charAt(i) != str.charAt(length-i-1)) return false; return true; } // Returns true if string formed by linked // list is palindrome boolean isPalindrome() { Node node = head; // Append all nodes to form a string String str = ""; while (node != null) { str = str.concat(node.data); node = node.next; } // Check if the formed string is palindrome return isPalidromeUtil(str); } /* Driver program to test above function*/ public static void main(String[] args) { LinkedList_Palindrome list = new LinkedList_Palindrome(); list.head = new Node("a"); list.head.next = new Node("bc"); list.head.next.next = new Node("d"); list.head.next.next.next = new Node("dcb"); list.head.next.next.next.next = new Node("a"); System.out.println(list.isPalindrome()); }}// This code has been contributed by Amit Khandelwal |
Python
# Python program to check if given linked list of # strings form a palindrome # Node class class Node: # Constructor to initialize the node object def __init__(self, data): self.data = data self.next = None class LinkedList: # Function to initialize head def __init__(self): self.head = None # A utility function to check if str is palindrome # or not def isPalindromeUtil(self, string): return (string == string[::-1]) # Returns true if string formed by linked list is # palindrome def isPalindrome(self): node = self.head # Append all nodes to form a string temp = [] while (node is not None): temp.append(node.data) node = node.next string = "".join(temp) return self.isPalindromeUtil(string) # Utility function to print the linked LinkedList def printList(self): temp = self.head while (temp): print temp.data, temp = temp.next # Driver program to test above functionllist = LinkedList()llist.head = Node('a')llist.head.next = Node('bc')llist.head.next.next = Node("d")llist.head.next.next.next = Node("dcb")llist.head.next.next.next.next = Node("a")print "true" if llist.isPalindrome() else "false" # This code is contributed by Nikhil Kumar Singh(nickzuck_007) |
C#
// C# Program to check if a given linked list // of strings form a palindrome using System; // Linked List node class Node { public String data; public Node next; public Node(String d) { data = d; next = null; } } public class LinkedList_Palindrome { Node head; // A utility function to check if // str is palindrome or not bool isPalidromeUtil(String str) { int length = str.Length; // Match characters from beginning and // end. for (int i = 0; i < length / 2; i++) if (str[i] != str[length - i - 1]) return false; return true; } // Returns true if string formed by linked // list is palindrome bool isPalindrome() { Node node = head; // Append all nodes to form a string String str = ""; while (node != null) { str = str+(node.data); node = node.next; } // Check if the formed string is palindrome return isPalidromeUtil(str); } /* Driver code*/ public static void Main(String[] args) { LinkedList_Palindrome list = new LinkedList_Palindrome(); list.head = new Node("a"); list.head.next = new Node("bc"); list.head.next.next = new Node("d"); list.head.next.next.next = new Node("dcb"); list.head.next.next.next.next = new Node("a"); Console.WriteLine(list.isPalindrome()); } } // This code has been contributed// by PrinciRaj1992 |
Output:
true
This article is contributed by Aditya Goel. Please write comments if you find anything incorrect, or you want to share more information about the topic discussed above
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