added get minimum element of stack without extra space

Data Structures/Stacks/get_minimum_element_of_stack_without_extra_space.cpp

@@ -0,0 +1,95 @@
+#include <iostream>
+
+using namespace std;
+
+int stack[50], minimum, top=-1,x;
+
+void push(int x)
+{
+    if (top==-1)
+    {
+        top++;
+        stack[top]=x;
+        minimum = x;
+    }
+    else
+    {
+        if (x<minimum)
+        {
+            top++;
+            stack[top]=2*x-minimum;
+            minimum = x;
+        }
+
+        else
+        {
+            top++;
+            stack[top]=x;
+        }
+
+    }
+}
+
+void pop()
+{
+    if (top ==-1)
+        cout << "Stack is Empty\n";
+    int d=stack[top];
+    top--;
+    if (d < minimum)
+        {
+            cout<<minimum<<" is deleted"<<endl;
+            minimum = 2*minimum- d;
+        }
+    else
+        cout<<d<<" is deleted"<<endl;
+}
+
+int getmin()
+{
+    if (top ==-1)
+        cout << "Stack is Empty\n";
+    cout <<"Minimum Element in the stack is: "<< minimum<< "\n";
+    return minimum;
+}
+
+
+int main()
+{
+    int choice,n;
+    cout<<"Enter size of the array: ";
+    cin>>n;
+
+    cout<<"1) Push"<<endl;
+    cout<<"2) Pop"<<endl;
+    cout<<"3) Minimum Element: "<<endl;
+    cout<<"4) Exit"<<endl;
+    do {
+      cout<<"Enter your choice: ";
+      cin>>choice;
+      switch(choice) {
+         case 1: {
+            cout<<"Enter the value to be entered in the stack: "<<endl;
+            cin>>x;
+            push(x);
+            break;
+         }
+         case 2: {
+            pop();
+            break;
+         }
+         case 3: {
+            int minimum=getmin();
+            break;
+         }
+         case 4: {
+            cout<<"Exit"<<endl;
+            break;
+         }
+         default: {
+            cout<<"Wrong Choice"<<endl;
+         }
+      }
+   }while(choice!=4);
+   return 0;
+}