DSA-codes/Queue.cpp at main · FreeDSA/DSA-codes · GitHub

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
#include<bits/stdc++.h>
#include<iostream>

using namespace std;

#define n 100

class Queue{
    int* arr;
    int front;
    int back;

    public:
    Queue(){
        arr=new int[n];
        front=-1;
        back=-1;
    }

    void push(int x){
        if(back==n-1){
            cout<<"Queue overflow"<<endl;
            return;
        }
        back++;
        arr[back]=x;
        if(front==-1){
            front++;
        }
    }
    void pop(){
        if(front==-1 || front>back){
            cout<<"Queue is empty"<<endl;
            return;
        }
        front++;
    }
    int peek(){
        if(front==-1 || front>back){
            cout<<"Queue is empty"<<endl;
            return -1;
        }
        return arr[front];
    }
    bool empty(){
        if(front==-1 || front>back){
            return 1;
        }
        return 0;
    }
};

int main(){

    Queue q;
    q.push(1);
    q.push(2);
    q.push(3);
    q.push(4);
    q.push(5);

    cout<<q.peek()<<endl;
    q.pop();
    cout<<q.peek()<<endl;
    q.pop();
    cout<<q.peek()<<endl;
    q.pop();
    cout<<q.peek()<<endl;
    q.pop();
    cout<<q.peek()<<endl;
    q.pop();

    cout<<q.empty()<<endl;
    return 0;
}