Merge pull request #779 from raunakjaiswal/queue/raunakjaiswal

fixes #776 issue

Author: vidit2512

queue/queue.cpp

@@ -0,0 +1,138 @@
+
+//@ raunak kumar jaiswal
+
+// function You can use is defined below:
+// 1. push()  - to insert a new data in queue
+// 2. pop() - to delete a data from a queue
+// 3. size() - to get the
+// 4. front() -  to get the front data stored in queue
+// 5. back() - to get the last stored data in queue
+// 6. isEmpty()- to check whether queue is empty or not
+
+#include <iostream>
+#include <cstdlib>
+using namespace std;
+template <class T1, class T2>
+
+class Pair
+{
+public:
+    T1 first;
+    T2 second;
+    Pair()
+    {
+    }
+    Pair(T1 x, T2 y)
+    {
+        first = x;
+        second = y;
+    }
+};
+template <class T>
+class Node
+{
+public:
+    T data;
+    Node<T> *next;
+    Node(T d)
+    {
+        data = d;
+        next = NULL;
+    }
+};
+template <class T>
+class Queue
+{
+    int sz;
+    Node<T> *rear;
+    Node<T> *fron;
+
+public:
+    Queue()
+    {
+        fron = rear = NULL;
+        sz = 0;
+    }
+
+    void push(T item)
+    {
+        Node<T> *temp = new Node<T>(item);
+        ++sz;
+        if (rear == NULL)
+        {
+            rear = temp;
+            fron = temp;
+            return;
+        }
+        rear->next = temp;
+        rear = temp;
+    }
+
+    void pop()
+    {
+        if (fron == NULL)
+            return;
+
+        Node<T> *temp = fron;
+        fron = fron->next;
+
+        delete (temp);
+        --sz;
+        if (fron == NULL)
+        {
+            sz = 0;
+            rear = NULL;
+        }
+    }
+    T front()
+    {
+        if (fron == NULL)
+        {
+            exit(0);
+        }
+        return fron->data;
+    }
+    int size()
+    {
+        return sz;
+    }
+    T back()
+    {
+        if (rear == NULL)
+        {
+            exit(0);
+        }
+        return rear->data;
+    }
+    bool isEmpty()
+    {
+        return fron == NULL;
+    }
+};
+
+int main()
+{
+
+    Queue<Pair<Pair<int, string>, int>> qq;
+
+    qq.push({{5, "data"}, 6});
+    qq.push({{6, "structure"}, 7});
+    qq.push({{7, "fcfs"}, 8});
+    qq.push({{8, "queue"}, 9});
+    qq.push({{9, "stl"}, 10});
+    qq.pop();
+
+    cout << qq.front().first.first << " " << qq.front().first.second << " " << qq.front().second << endl;
+
+    cout << qq.back().first.first << " " << qq.back().first.second << " " << qq.back().second << endl;
+
+    //while loop iterating over all elements and deleting
+    cout << "\n--- iterating over all elements -- \n"
+         << endl;
+    while (!qq.isEmpty())
+    {
+        cout << qq.front().first.first << " " << qq.front().first.second << " " << qq.front().second << endl;
+        qq.pop();
+    }
+    return 0;
+}