feat: Doubly linked list (#43)

* feat: Doubly linked list

Author: phumipatc

Data_Structure/Doubly_Linked_List.cpp

@@ -0,0 +1,119 @@
+/*
+	Task		: Doubly Linked List
+	Author		: Phumipat C.
+	Language	: C++
+	Explanation	: 
+*/
+#include <iostream>
+
+struct Node{
+	int data;
+	Node *next;
+	Node *prev;
+	Node(int val){
+		data = val;
+		next = NULL;
+		prev = NULL;
+	}
+};
+
+Node *create_node(int val){
+	Node *new_node = new Node(val);
+	return new_node;
+}
+
+void insert_node_after(Node *prev_node, int val){
+	if(prev_node == NULL){
+		cout << "The given previous node cannot be NULL";
+		return ;
+	}
+	Node *new_node = create_node(val);
+	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;
+	}
+}
+
+Node *move_backward(Node *node_to_move){
+	if(node_to_move == NULL || node_to_move->prev == NULL){
+		cout << "The given node cannot be NULL or the first node";
+		return node_to_move;
+	}
+
+	Node *prev_node = node_to_move->prev;
+	return prev_node;
+}
+
+Node *move_forward(Node *node_to_move){
+	if(node_to_move == NULL || node_to_move->next == NULL){
+		cout << "The given node cannot be NULL or the last node";
+		return node_to_move;
+	}
+
+	Node *next_node = node_to_move->next;
+	return next_node;
+}
+
+Node *move_to_front(Node *node_to_move){
+	if(node_to_move == NULL){
+		cout << "The given node cannot be NULL";
+		return node_to_move;
+	}
+
+	while(node_to_move->prev != NULL){
+		node_to_move = move_backward(node_to_move);
+	}
+	return node_to_move;
+}
+
+Node *move_to_end(Node *node_to_move){
+	if(node_to_move == NULL){
+		cout << "The given node cannot be NULL";
+		return node_to_move;
+	}
+
+	while(node_to_move->next != NULL){
+		node_to_move = move_forward(node_to_move);
+	}
+	return node_to_move;
+}
+
+void PrintCurrentNode(Node *current){
+	if(current == NULL){
+		cout << "The given node cannot be NULL";
+		return ;
+	}
+	cout << current->data << "\n";
+}
+
+int main()
+{
+	// Linked list: 1
+	Node *head = create_node(1);
+	Node *current = head;
+
+	// Linked list: 1 2
+	insert_node_after(head, 2);
+
+	// current pointing to 2
+	current = move_forward(head);
+
+	// Linked list: 1 2 3
+	insert_node_after(current, 3);
+
+	// current pointing to 1
+	current = move_to_front(current);
+
+	// Linked list: 1 4 2 3
+	insert_node_after(current, 4);
+
+	// current pointing to 3
+	current = move_to_end(current);
+
+	// Linked list: 1 4 2 3 5
+	insert_node_after(current, 5);
+
+	return 0;
+}