« Queues using LinkedList

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1#include <iostream>
2#include <iomanip>
3#include <algorithm>
4#include <string>
5#include <cstring>
6#include <vector>
7#include <cmath>
8#include <map>
9#include <climits>
10// climits for INT_MIN
11#include <unordered_map>
12using namespace std;
13
14template <typename T>
15class Node
16{
17public:
18    int data;
19    Node<T> *next;
20
21    Node(T data)
22    {
23        this->data = data;
24        next = NULL;
25    }
26};
27
28template <typename T>
29class Queue
30{
31    Node<T> *head;
32    Node<T> *tail;
33    int size;
34
35public:
36    Queue()
37    {
38        head = NULL;
39        tail = NULL;
40        size = 0;
41    }
42
43    int getSize() const
44    {
45        return size;
46    }
47
48    bool isEmpty() const { return size == 0; }
49
50    void enqueue(T element)
51    {
52        Node<T> *newNode = new Node<T>(element);
53        if (head == NULL)
54        {
55            head = tail = newNode;
56        }
57        else
58        {
59            tail->next = newNode;
60            tail = newNode;
61        }
62        size++;
63    }
64
65    T front()
66    {
67        if (size == 0)
68        {
69            return 0;
70        }
71        return head->data;
72    }
73
74    T dequeue()
75    {
76        if (size == 0)
77        {
78            return 0;
79        }
80        T ans = head->data;
81        Node<T> *next = head->next;
82        delete[] head;
83        head = next;
84        size--;
85        return ans;
86    }
87};
88
89int main()
90{
91    Queue<int> q;
92    q.enqueue(10);
93    q.enqueue(20);
94    q.enqueue(30);
95    q.enqueue(40);
96    q.enqueue(50);
97    q.enqueue(60);
98    q.enqueue(70);
99
100    cout << q.front() << endl;
101    cout << q.getSize() << endl;
102    q.dequeue();
103    q.dequeue();
104    q.dequeue();
105    cout << q.front() << endl;
106    cout << q.getSize() << endl;
107
108    return 0;
109}