From 10c569caead9222c9f758eb672ae145b7dd59abb Mon Sep 17 00:00:00 2001
From: Devansh <B20094@students.iitmandi.ac.in>
Date: Sun, 31 Oct 2021 05:30:08 +0530
Subject: [PATCH] Reversed Linked List

---
 C++/Reversed _linked_list.cpp | 79 +++++++++++++++++++++++++++++++++++
 contribution.md               |  1 +
 2 files changed, 80 insertions(+)
 create mode 100644 C++/Reversed _linked_list.cpp

diff --git a/C++/Reversed _linked_list.cpp b/C++/Reversed _linked_list.cpp
new file mode 100644
index 0000000..5236d69
--- /dev/null
+++ b/C++/Reversed _linked_list.cpp	
@@ -0,0 +1,79 @@
+#include <iostream>
+using namespace std;
+
+class ListNode {  //class of listNode
+    public:
+        int val;                //value sorted in node
+        ListNode *next;             //pointer to next node
+        ListNode(int x) : val(x), next(NULL) {}   //constructor
+};
+
+//Add new node to the end of the list and updates the end pointer
+void insert_at_tail(ListNode* &end,ListNode* &head,int val){
+    ListNode* n = new ListNode(val);        //new node
+
+    if(head==NULL){    //if the linked list is element , head and end pointer will points towards 1st node
+        head=n;
+        end=n;          //this condition hits only one time
+        return;
+    }
+    end->next=n;        //add pointer to the new node 
+    end=n;              //update end pointer
+}
+
+//reverses the linked list and updates pointer accordingly
+void Make_Reversed_Linked_List(ListNode* &end,ListNode* &head){
+    ListNode* temp=head;    //current node
+    ListNode* prev=NULL;    //previous node
+    ListNode* next=NULL;     //next node
+    ListNode* delta =head;    //pointer to current head
+
+    while(temp!=NULL){
+        next=temp->next;        //change pointer to previous node instead of next node 
+        temp->next=prev;        //to reverse the linked list
+        prev=temp;
+        temp=next;
+    }
+    head=prev;          //update head pointer
+    end=delta;         //update end pointer
+    end->next=NULL;      //end node points to nothing
+}
+
+//function to print the linked list (currently of no use but can be used to check our output)
+void print(ListNode* head){         
+    ListNode* temp=head;
+    while(temp!=NULL){              //check condition if pointer to next element is null then terminates it
+        cout<<temp->val<<" ";       //print node then move to next node
+        temp=temp->next;
+    }
+}
+
+int main(){
+    
+    cout<<"Enter number of nodes in Linked List"<<endl;
+    int n;              //taking input of number of nodes
+    cin>>n;
+
+    if( n==0){              //terminates the code if total nodes = 0
+        cout<<"Size of linked list is 0, please enter size greater than 0 ";
+        return 0;
+    }
+
+    cout<<"Enter elements of linked list"<<endl; 
+    ListNode* head=NULL;   //head pointer
+    ListNode* end = NULL;   //end pointer(initially both null)
+
+    for (int i=0;i<n;i++){
+        int a;                          //input the value saved in node
+        cin>>a;
+        insert_at_tail(end,head,a);     //adds node to tail of linked list
+    }
+
+    Make_Reversed_Linked_List(end,head);        //reverses the linked list and also update head and end pointer 
+                                                //accordingly
+    cout<<"Reversed Linked list  : ";
+    print(head);
+    
+    
+    return 0;
+}
\ No newline at end of file
diff --git a/contribution.md b/contribution.md
index 180ca24..03da2cd 100644
--- a/contribution.md
+++ b/contribution.md
@@ -10,3 +10,4 @@
 [meghala](https://github.com/m3gh4l4)
 [xharsshvardhan](https://github.com/xharshvardhan)
 [Deumus74](https://github.com/Deumus74)
+[Devansh0901](https://github.com/Devansh0901)