Why this code is giving segmentation fault in linked list intersection? - linked-list

Question

// Online C++ compiler to run C++ program online
#include <bits/stdc++.h>
using namespace std;
struct Node{
int data;
Node *next;
Node(int val)
{
data=val;
next=NULL;
}
};
Node* findIntersection(Node* head1, Node* head2)
{
// Your Code Here
Node* h=nullptr;
Node* temp=h;
while(head2!=nullptr){
while(head1!=nullptr && head1->data<head2->data){
head1=head1->next;
}
cout<<head1->data<<endl;
if(head1->data==head2->data){
if(h==nullptr){
h=new Node(head1->data);
}
else{
temp->next=new Node(head1->data);
temp=temp->next;
}
}
head2=head2->next;
}
return h;
}
int main() {
// Write C++ code here
Node* l1= new Node(1);
l1->next=new Node(2);
l1->next->next=new Node(3);
l1->next->next->next=new Node(4);
l1->next->next->next->next=new Node(6);
Node* l2=new Node(2);
l1->next=new Node(4);
l1->next->next=new Node(6);
l1->next->next->next=new Node(8);
findIntersection(l1,l2);
return 0;
}
I tried to find intersection of two linked lists with elements in sorted order.
This is a question on GFG which can be found on link:
https://practice.geeksforgeeks.org/problems/intersection-of-two-sorted-linked-lists/1?page=1&category[]=Linked%20List&sortBy=difficulty

Answer 1

Why this code is giving segmentation fault in linked list intersection?
Because there are bugs in it. You'll benefit from learning how to debug small programs.
#include <bits/stdc++.h>
Unrelated to your crash, but you should never #include anything from the bits directory.
while(head2!=nullptr){
while(head1!=nullptr && head1->data<head2->data){
head1=head1->next;
}
// We could get here if head1==nullptr. The next line will crash.
cout<<head1->data<<endl;
...
else {
// temp was assigned NULL in the start, and now is being dereferenced.
temp->next=new Node(head1->data);
temp=temp->next;
}