Data Structure
Networking
RDBMS
Operating System
Java
MS Excel
iOS
HTML
CSS
Android
Python
C Programming
C++
C#
MongoDB
MySQL
Javascript
PHP
Physics
Chemistry
Biology
Mathematics
English
Economics
Psychology
Social Studies
Fashion Studies
Legal Studies
- Selected Reading
- UPSC IAS Exams Notes
- Developer's Best Practices
- Questions and Answers
- Effective Resume Writing
- HR Interview Questions
- Computer Glossary
- Who is Who
Implement Stack using Queues in C++
Suppose we want to implement one stack using a queue. We have to define these methods for the stack.
push(x) − Push x onto stack.
pop() − Delete and return top element from stack
top() − Return the top element from stack.
empty() − Return whether the stack is empty or not.
So, if we call the functions push(10), push(20), then call pop(), pop(), then the output will be 20, 10
To solve this, we will follow these steps −
Define one deque q
Define a function push(), this will take x,
insert x at the beginning of q
Define a function pop()
k := first element of q
delete front element from q
return k
Define a function top()
return first element of q
Define a function empty()
if q is empty, then −
return true
Otherwise
return false
Example
Let us see the following implementation to get a better understanding −
#include <bits/stdc++.h>
using namespace std;
class MyStack {
private:
deque<int> q;
public:
void push(int x){
q.push_front(x);
}
int pop(){
int k = q.front();
q.pop_front();
return k;
}
int top(){
return q.front();
}
bool empty(){
if (q.empty())
return true;
else
return false;
}
};
main(){
MyStack ob;
ob.push(10);
ob.push(20);
cout << (ob.pop()) << endl;
cout << (ob.pop()) << endl;
}Input
push(10),push(20),pop(),pop()
Output
20 10
3K+ Views
