Added Doubly linked list functionality.

Linked Lists/Doubly Linked Lists/Function.cpp

@@ -0,0 +1,286 @@
+#include<stdio.h>
+#include<stdlib.h>
+#include<iostream>
+using namespace std;
+struct Node
+{
+	int data;
+	struct Node *next;
+	struct Node *prev;
+};
+
+void push(struct Node** head_ref, int new_data)
+{
+
+	struct Node* new_node = (struct Node*)malloc(sizeof(struct Node));
+
+	new_node->data = new_data;
+
+	new_node->next = (*head_ref);
+	new_node->prev = NULL;
+
+	if((*head_ref) != NULL )
+		(*head_ref)->prev = new_node;
+
+	(*head_ref) = new_node;
+}
+
+void insertAfter(struct Node* prev_node, int new_data) 
+{ 
+
+    if (prev_node == NULL) { 
+        printf("the given previous node cannot be NULL"); 
+        return; 
+    } 
+
+
+    struct Node* new_node = (struct Node*)malloc(sizeof(struct Node)); 
+
+
+    new_node->data = new_data; 
+
+
+    new_node->next = prev_node->next; 
+
+
+    prev_node->next = new_node; 
+
+
+    new_node->prev = prev_node; 
+
+
+    if (new_node->next != NULL) 
+        new_node->next->prev = new_node; 
+}
+
+void append(struct Node** head_ref, int new_data) 
+{ 
+
+    struct Node* new_node = (struct Node*)malloc(sizeof(struct Node)); 
+
+    struct Node* last = *head_ref;  
+
+    new_node->data = new_data; 
+
+
+    new_node->next = NULL; 
+
+
+    if (*head_ref == NULL) { 
+        new_node->prev = NULL; 
+        *head_ref = new_node; 
+        return; 
+    } 
+
+
+    while (last->next != NULL) 
+        last = last->next; 
+
+    last->next = new_node; 
+
+
+    new_node->prev = last; 
+
+    return; 
+} 
+
+void insertBefore(struct Node** head_ref, struct Node* next_node, int new_data)  
+{  
+
+    if (next_node == NULL) {  
+        printf("the given next node cannot be NULL");  
+        return;  
+    }  
+
+
+    struct Node* new_node = (struct Node*)malloc(sizeof(struct Node));  
+
+
+    new_node->data = new_data;  
+
+
+    new_node->prev = next_node->prev;  
+
+
+    next_node->prev = new_node;  
+
+
+    new_node->next = next_node;  
+
+
+    if (new_node->prev != NULL)  
+        new_node->prev->next = new_node;  
+    else
+        (*head_ref) = new_node; 
+}
+
+void printList(Node* node)  
+{  
+    Node* last;  
+    cout<<"\nTraversal in forward direction \n";  
+    while (node != NULL)  
+    {  
+        cout<<" "<<node->data<<" ";  
+        last = node;  
+        node = node->next;  
+    }  
+
+    cout<<"\nTraversal in reverse direction \n";  
+    while (last != NULL)  
+    {  
+        cout<<" "<<last->data<<" ";  
+        last = last->prev;  
+    }  
+}
+
+void reverse(Node **head_ref)  
+{  
+    Node *temp = NULL;  
+    Node *current = *head_ref;  
+
+
+    while (current != NULL)  
+    {  
+        temp = current->prev;  
+        current->prev = current->next;  
+        current->next = temp;              
+        current = current->prev;  
+    }  
+
+
+    if(temp != NULL )  
+        *head_ref = temp->prev;  
+}  
+
+void swap(int *A, int *B)  
+{  
+    int temp = *A;  
+    *A = *B;  
+    *B = temp;  
+}  
+
+Node *split(Node *head)  
+{  
+    Node *fast = head,*slow = head;  
+    while (fast->next && fast->next->next)  
+    {  
+        fast = fast->next->next;  
+        slow = slow->next;  
+    }  
+    Node *temp = slow->next;  
+    slow->next = NULL;  
+    return temp;  
+}    
+
+
+Node *merge(Node *first, Node *second)  
+{  
+
+    if (!first)  
+        return second;  
+
+
+    if (!second)  
+        return first;  
+
+
+    if (first->data < second->data)  
+    {  
+        first->next = merge(first->next,second);  
+        first->next->prev = first;  
+        first->prev = NULL;  
+        return first;  
+    }  
+    else
+    {  
+        second->next = merge(first,second->next);  
+        second->next->prev = second;  
+        second->prev = NULL;  
+        return second;  
+    }  
+}  
+
+
+Node *mergeSort(Node *head)  
+{  
+    if (!head || !head->next)  
+        return head;  
+    Node *second = split(head);  
+
+
+    head = mergeSort(head);  
+    second = mergeSort(second);  
+
+
+    return merge(head,second);  
+}  
+
+//added swap node functionality by changing pointers instead of data
+
+void swapNodes(Node **head_ref, int x, int y)  
+{  
+
+if (x == y) return;  
+
+
+Node *prevX = NULL, *currX = *head_ref;  
+while (currX && currX->data != x)  
+{  
+    prevX = currX;  
+    currX = currX->next;  
+}  
+
+
+Node *prevY = NULL, *currY = *head_ref;  
+while (currY && currY->data != y)  
+{  
+    prevY = currY;  
+    currY = currY->next;  
+}  
+
+
+if (currX == NULL || currY == NULL)  
+    return;  
+
+
+if (prevX != NULL)  
+    prevX->next = currY;  
+else  
+    *head_ref = currY;  
+
+
+if (prevY != NULL)  
+    prevY->next = currX;  
+else 
+    *head_ref = currX;  
+
+
+Node *temp = currY->next;  
+currY->next = currX->next;  
+currX->next = temp;  
+}
+
+
+//added main function to check the swap functionality of the pointer nodes
+int main()  
+{  
+    Node *start = NULL;  
+
+    push(&start, 7);  
+    push(&start, 6);  
+    push(&start, 5);  
+    push(&start, 4);  
+    push(&start, 3);  
+    push(&start, 2);  
+    push(&start, 1);  
+
+    cout << "Linked list before calling swapNodes() ";  
+    printList(start);  
+
+    swapNodes(&start, 4, 3);  
+
+    cout << "\nLinked list after calling swapNodes() ";  
+    printList(start);  
+
+    return 0;  
+}