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Delete middle of linked list in C++ program
In this tutorial, we are going to learn how to delete the middle node in a linked list.
The solution to the problem is straightforward. We will have two pointers one moves one node at a time and the other one moves two nodes at a time. By the time the second pointer reaches the final node, the first will be in the middle of the linked list.
Let's see the steps to solve the problem.
Write a struct Node for the linked list node.
Initialize the linked list with the dummy data.
Write a function to delete the linked list.
Initialize two-pointers (slow and fast) with linked list head pointer.
Iterate over the linked list until the fast pointer reaches the end.
Move the slow pointer to one next node.
Move the fast pointer to the next node of the next node.
Return the head pointer
Print the linked list.
Example
Let's see the code.
#include <bits/stdc++.h>
using namespace std;
struct Node {
int data;
struct Node* next;
};
struct Node* deleteMiddleNode(struct Node* head) {
if (head == NULL) {
return NULL;
}
if (head->next == NULL) {
delete head;
return NULL;
}
struct Node* slow_ptr = head;
struct Node* fast_ptr = head;
struct Node* prev;
while (fast_ptr != NULL && fast_ptr->next != NULL) {
fast_ptr = fast_ptr->next->next;
prev = slow_ptr;
slow_ptr = slow_ptr->next;
}
prev->next = slow_ptr->next;
delete slow_ptr;
return head;
}
void printLinkedList(struct Node* node) {
while (node != NULL) {
cout << node->data << " -> ";
node = node->next;
}
cout << "Null" << endl;
}
Node* newNode(int data) {
struct Node* temp = new Node;
temp->data = data;
temp->next = NULL;
return temp;
}
int main() {
struct Node* head = newNode(1);
head->next = newNode(2);
head->next->next = newNode(3);
head->next->next->next = newNode(4);
head->next->next->next->next = newNode(5);
head->next->next->next->next->next = newNode(6);
cout << "Linked list before deleting middle node: ";
printLinkedList(head);
head = deleteMiddleNode(head);
cout << "Linked List after deleting middle node: ";
printLinkedList(head);
return 0;
}Output
If you execute the above program, then you will get the following result.
Linked list before deleting middle node: 1 -> 2 -> 3 -> 4 -> 5 -> 6 -> Null Linked List after deleting middle node: 1 -> 2 -> 3 -> 5 -> 6 -> Null
Conclusion
If you have any queries in the tutorial, mention them in the comment section.
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