Added stack using linked list in c++ folder

C++/Stack/stack_linked-list.cpp

@@ -0,0 +1,126 @@
+#include <iostream>
+using namespace std;
+
+/* Steps:
+    - Create linked list node which stores value(data), next(pointer), min(current min element)
+    - while pushing elements :
+        - if stack is empty store current val in min 
+        - if current element is less than min than store (2*x – minEle) in min
+    - while poping elements : 
+        - if current element is min restore as (2*minEle – y)
+    - Time complexity of push is O(1)
+    - Time complexity of pop is O(1)
+    - Time complexity of getmin is O(1)
+*/
+
+// Structure of Linked list Node:-
+struct Node{
+	int val; // value 
+	struct Node* next; // pointer to next node 
+	int min;
+};
+
+// Creating stack class with push, pop, getmin functions 
+class stack{
+    struct Node* top;
+    int min;
+public:
+    stack(){
+        top=NULL;
+    }
+    void push(int value) // Push function 
+    {
+        /*
+            - if(top == NULL) push the node and min -> value
+            - if(value > min) push the node and no need to change min
+            - if(value < min) push the node and store 2 * current min - value -> node.min and update min -> value 
+        */
+        Node* ptr;
+        if(top==NULL)
+        {
+            ptr=new Node;
+            ptr->val=value;
+            ptr->next=NULL;
+            ptr->min=value;
+            min = value;
+            top=ptr;
+        }
+        else if(value > min)
+        {
+            ptr=new Node;
+            ptr->val=value;
+            ptr->next=top;
+            ptr->min=value;
+            top=ptr;
+        }
+        else
+        {
+            ptr=new Node;
+            ptr->val=value;
+            ptr->next=top;
+            ptr->min=2*value - min;
+            top=ptr;
+            min = value;
+        }
+
+    }
+    void pop() // Pop function 
+    {
+        // if poped element is minimum restore the 2nd min value : min -> 2*min - node.min
+
+        Node* temp;
+        if(top == NULL)
+        {
+            cout<<endl<<-1;
+            return;
+        }
+        temp= top;
+        if (temp->min < min) 
+        {
+            min = 2*min - top->min;
+        }
+        top=top->next;
+        cout<<temp->val<<" ";
+        delete temp;
+    }
+    void print(){
+        Node* temp1=top;
+        cout<<"Stack : ";
+        while (temp1!=NULL){
+            cout<<temp1->val<<" ";
+            temp1=temp1->next;
+        }
+        cout<<endl;
+    }
+    void getmin() // Getmin function 
+    {
+        cout<<"Minimum element : "<<min<<endl;
+    }
+};
+
+int main() 
+{
+    //freopen("input.txt","r", stdin);
+    //freopen("output.txt","w", stdout);
+
+    // Calling stack class 
+    stack s;
+    int n,a; // n is the number of elements pushed 
+    cin>>n;
+    for(int i=0;i<n;i++)
+    {
+        cin>>a;
+        s.push(a); // Push elements 
+    }
+    s.print(); // Print the current stack 
+    cin>>n; // n is the number of elements popped 
+    cout<<"Popped elements : ";
+    for(int i=0;i<n;i++)
+    {
+        s.pop(); // Pop elements 
+    }
+    cout<<endl;
+    s.print(); // Print the current stack 
+    s.getmin(); // get minimum element in the present stack 
+    return 0;
+}

README.md

@@ -6,6 +6,7 @@
   * Stack
     * without STL
     * with STL
+    * using linked list 
   * Queue
     * without STL
     * Priority Queue with STL