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Merge pull request #1044 from shashanksh2000/patch-1
Added insertion program for linked lists.
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Program's_Contributed_By_Contributors/C++_Programs/Linked List/Insertion.cpp
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// A complete working C++ program to demonstrate | ||
// all insertion methods on Linked List | ||
#include <bits/stdc++.h> | ||
using namespace std; | ||
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// A linked list node | ||
class Node | ||
{ | ||
public: | ||
int data; | ||
Node *next; | ||
}; | ||
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/* Given a reference (pointer to pointer) | ||
to the head of a list and an int, inserts | ||
a new node on the front of the list. */ | ||
void push(Node** head_ref, int new_data) | ||
{ | ||
/* 1. allocate node */ | ||
Node* new_node = new Node(); | ||
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/* 2. put in the data */ | ||
new_node->data = new_data; | ||
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/* 3. Make next of new node as head */ | ||
new_node->next = (*head_ref); | ||
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/* 4. move the head to point to the new node */ | ||
(*head_ref) = new_node; | ||
} | ||
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/* Given a node prev_node, insert a new node after the given | ||
prev_node */ | ||
void insertAfter(Node* prev_node, int new_data) | ||
{ | ||
/*1. check if the given prev_node is NULL */ | ||
if (prev_node == NULL) | ||
{ | ||
cout<<"The given previous node cannot be NULL"; | ||
return; | ||
} | ||
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/* 2. allocate new node */ | ||
Node* new_node = new Node(); | ||
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/* 3. put in the data */ | ||
new_node->data = new_data; | ||
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/* 4. Make next of new node as next of prev_node */ | ||
new_node->next = prev_node->next; | ||
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/* 5. move the next of prev_node as new_node */ | ||
prev_node->next = new_node; | ||
} | ||
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/* Given a reference (pointer to pointer) to the head | ||
of a list and an int, appends a new node at the end */ | ||
void append(Node** head_ref, int new_data) | ||
{ | ||
/* 1. allocate node */ | ||
Node* new_node = new Node(); | ||
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Node *last = *head_ref; /* used in step 5*/ | ||
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/* 2. put in the data */ | ||
new_node->data = new_data; | ||
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/* 3. This new node is going to be | ||
the last node, so make next of | ||
it as NULL*/ | ||
new_node->next = NULL; | ||
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/* 4. If the Linked List is empty, | ||
then make the new node as head */ | ||
if (*head_ref == NULL) | ||
{ | ||
*head_ref = new_node; | ||
return; | ||
} | ||
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/* 5. Else traverse till the last node */ | ||
while (last->next != NULL) | ||
{ | ||
last = last->next; | ||
} | ||
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/* 6. Change the next of last node */ | ||
last->next = new_node; | ||
return; | ||
} | ||
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// This function prints contents of | ||
// linked list starting from head | ||
void printList(Node *node) | ||
{ | ||
while (node != NULL) | ||
{ | ||
cout<<" "<<node->data; | ||
node = node->next; | ||
} | ||
} | ||
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/* Driver code*/ | ||
int main() | ||
{ | ||
/* Start with the empty list */ | ||
Node* head = NULL; | ||
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// Insert 6. So linked list becomes 6->NULL | ||
append(&head, 6); | ||
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// Insert 7 at the beginning. | ||
// So linked list becomes 7->6->NULL | ||
push(&head, 7); | ||
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// Insert 1 at the beginning. | ||
// So linked list becomes 1->7->6->NULL | ||
push(&head, 1); | ||
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// Insert 4 at the end. So | ||
// linked list becomes 1->7->6->4->NULL | ||
append(&head, 4); | ||
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// Insert 8, after 7. So linked | ||
// list becomes 1->7->8->6->4->NULL | ||
insertAfter(head->next, 8); | ||
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cout<<"Created Linked list is: "; | ||
printList(head); | ||
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return 0; | ||
} |