Rearrange a linked list such that all even and odd positioned nodes a…

…re together

LLevenoddarrange.cpp

@@ -0,0 +1,126 @@
+#include<iostream>
+using namespace std;
+class node
+{
+public:
+	int data;
+	node*next;
+
+	node(int d)
+	{
+		data=d;
+		next=NULL;
+	}
+};
+
+void insertathead(node*&head,int data)
+{
+	node*n=new node(data);
+	n->next=head;
+	head=n;
+}
+
+void insertatend(node*&head,int data)
+{
+	if(head==NULL)
+	{
+		insertathead(head,data);
+	}
+
+	else
+	{
+		node*temp=head;
+		while(temp->next!=NULL)
+		{
+			temp=temp->next;
+		}
+		node*tail=new node(data);
+		temp->next=tail;
+	}
+}
+
+void Buildlist(node*&head)
+{
+	int data;
+	cin>>data;
+	while(data!=-1)
+
+	{
+		insertatend(head,data);
+		cin>>data;
+	}
+
+
+}
+void print(node*head)
+{
+	while(head!=NULL)
+	{
+		cout<<head->data<<"->";
+		head=head->next;
+	}
+	cout<<endl;
+}
+
+
+
+
+node* rearrange(node*&head)
+{	
+	//Initialize first node of odd and even lists
+	node*odd=head;
+	node*even=head->next;
+
+	//remember the first node of even list
+	node*evenfirst=even;
+	node*head1=new node(0);
+
+
+	while(1)
+	{
+		if(odd==NULL || even==NULL || even->next==NULL)
+		{
+			odd->next=evenfirst;
+			break;
+		}
+		//Jump to next odd node and update the odd node
+		odd->next=even->next;
+		odd=even->next;
+
+		//if the nodes are over than point the next of odd 
+		//to the first node of even list
+		if(odd->next==NULL)
+		{
+			even->next=NULL;
+			odd->next=evenfirst;
+			break;
+		}
+
+		//Jump to next even node and update the even node
+		even->next=odd->next;
+		even=odd->next;
+	}
+
+	return head;
+
+}
+
+
+
+
+
+
+
+int main()
+{
+	node*head=NULL;
+	Buildlist(head);
+
+	print(head);
+
+	head=rearrange(head);
+	print(head);
+	return 0;
+
+
+}