diff --git a/linked-lists/README.md b/linked-lists/README.md index 5d632318..46b4e94c 100644 --- a/linked-lists/README.md +++ b/linked-lists/README.md @@ -12,6 +12,7 @@ 2. [Doubly Linked List](c-or-cpp/doubly.cpp) 3. [Circular Linked List](c-or-cpp/circular.cpp) +4. [Insertion Linked List](c-or-cpp/all-possible-insertion.cpp) ### Java diff --git a/linked-lists/c-or-cpp/all-possible-insertion.cpp b/linked-lists/c-or-cpp/all-possible-insertion.cpp new file mode 100644 index 00000000..01839891 --- /dev/null +++ b/linked-lists/c-or-cpp/all-possible-insertion.cpp @@ -0,0 +1,135 @@ +/*A node can be added in three ways +1) At the front of the linked list +2) After a given node. +3) At the end of the linked list.*/ + +// all insertion methods on Linked List + +#include +using namespace std; + +// A linked list node +class Node +{ + public: + int data; + Node *next; +}; + +/* 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(); + + /* 2. put in the data */ + new_node->data = new_data; + + /* 3. Make next of new node as head */ + new_node->next = (*head_ref); + + /* 4. move the head to point to the new node */ + (*head_ref) = new_node; +} + +/* 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; + } + + /* 2. allocate new node */ + Node* new_node = new Node(); + + /* 3. put in the data */ + new_node->data = new_data; + + /* 4. Make next of new node as next of prev_node */ + new_node->next = prev_node->next; + + /* 5. move the next of prev_node as new_node */ + prev_node->next = new_node; +} + +/* 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(); + + Node *last = *head_ref; /* used in step 5*/ + + /* 2. put in the data */ + new_node->data = new_data; + + /* 3. This new node is going to be + the last node, so make next of + it as NULL*/ + new_node->next = NULL; + + /* 4. If the Linked List is empty, + then make the new node as head */ + if (*head_ref == NULL) + { + *head_ref = new_node; + return; + } + + /* 5. Else traverse till the last node */ + while (last->next != NULL) + last = last->next; + + /* 6. Change the next of last node */ + last->next = new_node; + return; +} + +// This function prints contents of +// linked list starting from head +void printList(Node *node) +{ + while (node != NULL) + { + cout<<" "<data; + node = node->next; + } +} + +/* Driver code*/ +int main() +{ + /* Start with the empty list */ + Node* head = NULL; + + // Insert 6. So linked list becomes 6->NULL + append(&head, 6); + + // Insert 7 at the beginning. + // So linked list becomes 7->6->NULL + push(&head, 7); + + // Insert 1 at the beginning. + // So linked list becomes 1->7->6->NULL + push(&head, 1); + + // Insert 4 at the end. So + // linked list becomes 1->7->6->4->NULL + append(&head, 4); + + // Insert 8, after 7. So linked + // list becomes 1->7->8->6->4->NULL + insertAfter(head->next, 8); + + cout<<"Created Linked list is: "; + printList(head); + + return 0; +}