CODEWITHSUNDEEP
c++linked-listpalindrome
Garvit
Garvit

Reputation: 94

Linked List is Palindrome or not

I'm new to Linked List and I was trying to solve this question where we have to return true or false on the basis of whether given linked List is palindrome or not.

Given a pointer to the 1st node.

bool isPalindrome(Node *head)
{
    //Your code here
    Node *startsecond = NULL;//will act as pointer to second Linked list 
    Node *temp2 = head; 
    Node *temp1 = head;
    
    //Split LINKED LIST IN 2 PARTS
    while(1){
        temp2 = temp2->next->next;
        if(temp2->next==NULL){//if linked list has odd no of elements
            startsecond = temp1->next->next;
            break;
        }else{
            startsecond = temp1->next;
            break;
        }
        temp1 = temp1->next;
    }
    temp1->next=NULL;
    
    //REVERSE THE SECOND LINKED LIST
    Node *current = startsecond; 
    Node *prev = NULL, *next = NULL;
    while(current!=NULL){
        next = current->next;
        current->next = prev;
        prev=current;
        current=next;
    }
    startsecond = prev;
    
    while(head!=NULL && startsecond!=NULL){
        if(startsecond->data == head->data){
            head = head->next;
            startsecond = startsecond->next;
        }
        else
        return false;
    }
    return true;
}

I'm not able to understand it gives segmentation error. It says:

Runtime Error:
Runtime ErrorSegmentation Fault (SIGSEGV)

Here I'm first splitting the Linked List into 2 equal halves and then reverse the second half and then compare the elements to 2 one by one. Can someone please help debug.

Upvotes: 0

Views: 62

Answers (1)

cigien
cigien

Reputation: 60218

You have a typo here:

Node *temp2 = head,  // , instead of ;
Node *temp1 = head;

Notice the , instead of a ;.

You need:

Node *temp2 = head;
Node *temp1 = head;

or

Node *temp2 = head, *temp1 = head;

Upvotes: 1

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