Queue Programs

altruistcoder · altruistcoder · commit 5bc5dae38672 · 2019-06-01T04:12:54.000+05:30
diff --git a/Queue/queue_using_stack.cpp b/Queue/queue_using_stack.cpp
@@ -0,0 +1,71 @@
+#include <bits/stdc++.h>
+using namespace std;
+
+struct Queue {
+    stack<int> s1, s2;
+    // Add an item to the queue
+    void enQueue(int x)
+    {
+        // Push item into the first stack (s1)
+        s1.push(x);
+    }
+    // Remove an item from the queue
+    int deQueue()
+    {
+        // If both stacks are empty, then exit
+        if (s1.empty() && s2.empty()){
+            cout << "Q is empty";
+            exit(0);
+        }
+
+        // If second stack (s2) is empty, move elements from first stack (s1) to second stack (s2)
+        if (s2.empty()) {
+            while (!s1.empty()){
+                s2.push(s1.top());
+                s1.pop();
+            }
+        }
+        // Return the top item from secodn stack (s2)
+        int x = s2.top();
+        s2.pop();
+        return x;
+    }
+    void sizeQueue()
+    {
+        cout<<"Size of the Queue: "<<s1.size()+s2.size()<<endl;
+    }
+};
+
+int main()
+{
+    Queue q;
+    int x, data;
+    char ch;
+    do
+    {
+    cout<<"\t Main Menu \n";
+    cout<<"\t 1. Insertion to Queue \n";
+    cout<<"\t 2. Deletion from Queue \n";
+    cout<<"\t 3. Size of Queue\n";
+    cout<<"\t 4. Quit \n";
+    cout<<"Enter your choice: ";
+    cin>>x;
+    switch(x)
+    {
+        case 1: cout<<"Enter the value to be inserted in Queue: ";
+                cin>>data;
+                q.enQueue(data);
+                break;
+        case 2: cout<<"The deleted element is: "<<q.deQueue()<<endl;
+                break;
+        case 3: q.sizeQueue();
+                break;
+        case 4: exit(0);
+        default: cout<<"Wrong Choice Entered\n";
+    }
+    cout<<"Do you want to go to the main menu (y/n): ";
+    cin>>ch;
+    }
+    while(ch=='Y'||ch=='y');
+    return 0;
+}
diff --git a/README.md b/README.md
@@ -4,6 +4,10 @@ This is a repository containing various C++ Programs to understand the basic con
 
 ## Programs
 
+* [Queue Using Stack](https://github.com/altruistcoder/Data-Structures/blob/master/Queue/queue_using_stack.cpp):
+
+  C++ Code for implementing a queue using stacks.
+
 * [Merge Sort](https://github.com/altruistcoder/Data-Structures/blob/master/Sorting%20Programs/merge_sort.cpp):
 
   C++ Code for implementing Merge Sort algorithm.
