Implementing Stack Using Single Queue

altruistcoder · altruistcoder · commit 738cf2afdfe9 · 2019-06-02T01:58:20.000+05:30
diff --git a/Stack/stack_using_single_queue.cpp b/Stack/stack_using_single_queue.cpp
@@ -0,0 +1,97 @@
+#include <bits/stdc++.h>
+using namespace std;
+
+class Stack
+{
+    // Initailize objects of two in-built queues.
+    queue<int>q;
+    // To maintain current size of stack
+    int curr_size;
+
+    public:
+        Stack()
+        {
+            curr_size = 0;
+        }
+
+        // Add an element to the Stack
+        void push(int x)
+        {
+            // Get previous size of queue
+            int s = q.size();
+            // Push current element to queue
+            q.push(x);
+            // Dequeue all previous elements and Enqueue them after current element
+            for (int i=0; i<s; i++)
+            {
+                // This will add element at front into rear of the queue
+                q.push(q.front());
+                // This will delete element at front of the queue
+                q.pop();
+            }
+            curr_size++;
+        }
+
+        // Remove an element from the Stack
+        void pop(){
+            if (q.empty())
+            {
+                cout << "Stack is Empty, thus deletion cannot be performed\n";
+                return;
+            }
+            cout<<"The popped element is: "<<q.front()<<endl;
+            q.pop();
+            curr_size--;
+            return;
+        }
+
+        void top()
+        {
+            if (q.empty())
+            {
+                cout<<"Stack is Empty\n";
+                return;
+            }
+            cout<<"The Top Element of Stack is: "<<q.front()<<endl;
+            return;
+        }
+
+        int sizeStack()
+        {
+            cout<<"Size of the Stack: "<<curr_size<<endl;
+        }
+};
+
+int main()
+{
+    Stack s;
+    int x, data;
+    do
+    {
+        cout<<"Main Menu \n";
+        cout<<"1. Insertion to Stack (Push Operation) \n";
+        cout<<"2. Deletion from Stack (Pop Operation) \n";
+        cout<<"3. Return Top Element from Stack \n";
+        cout<<"4. Size of Stack\n";
+        cout<<"5. Quit \n";
+        cout<<"Enter your choice (1-5): ";
+        cin>>x;
+        switch(x)
+        {
+            case 1: cout<<"Enter the value to be inserted in Stack: ";
+                    cin>>data;
+                    s.push(data);
+                    break;
+            case 2: s.pop();
+                    break;
+            case 3: s.top();
+                    break;
+            case 4: s.sizeStack();
+                    break;
+            case 5: exit(0);
+            default: cout<<"Invalid Choice Entered\n";
+        }
+    }
+    while(true);
+    return 0;
+}
