Answer to Question #273345 in C++ for Korea

Question

insert node at specific Position?

Answer 1

#include <bits/stdc++.h>
using namespace std;


// A linked list Node
struct Node {
	int data;
	struct Node* next;
};


// Size of linked list
int size = 0;


// function to create and return a Node
Node* getNode(int data)
{
	// allocating space
	Node* newNode = new Node();


	// inserting the required data
	newNode->data = data;
	newNode->next = NULL;
	return newNode;
}


// function to insert a Node at required position
void insertPos(Node** current, int pos, int data)
{
	// This condition to check whether the position given is valid or not.
	if (pos < 1 || pos > size + 1)
		cout << "Invalid position!" << endl;
	else {
		while (pos--) {


			if (pos == 0) {


				// adding Node at required position
				Node* temp = getNode(data);


				// Making the new Node to point to
				// the old Node at the same position
				temp->next = *current;


				// Changing the pointer of the Node previous to the old Node to point to the new Node
				*current = temp;
			}
			else
			// pointer pointing to the address of next Node
			current = &(*current)->next;
		}
		size++;
	}
}


// This function prints contents of the linked list
void printList(struct Node* head)
{
	while (head != NULL) {
		cout << " " << head->data;
		head = head->next;
	}
	cout << endl;
}
int main()
{
	// Creating the list 3,5,8,10
	Node* head = NULL;
	head = getNode(3);
	head->next = getNode(5);
	head->next->next = getNode(8);
	head->next->next->next = getNode(10);


	size = 4;


	cout << "Linked list before insertion: ";
	printList(head);


	int data = 12, pos = 3;
	insertPos(&head, pos, data);
	cout << "Linked list after insertion of 12 at position 3: ";
	printList(head);


	// front of the linked list
	data = 1, pos = 1;
	insertPos(&head, pos, data);
	cout << "Linked list after insertion of 1 at position 1: ";
	printList(head);


	// insertion at end of the linked list
	data = 15, pos = 7;
	insertPos(&head, pos, data);
	cout << "Linked list after insertion of 15 at position 7: ";
	printList(head);


	return 0;
}