QUESTION-
You need to implement a Stack class using linked list. The data members should be private. Implement the following public functions :
1. Constructor -
Initialises the data member (i.e. head to null).
2. push :
This function should take one argument of type int and has return type void. This function should insert an element in the stack. Time complexity should be O(1).
3. pop :
This function takes no input arguments and has return type int. This should removes the last element which is entered and return that element as an answer. Return 0 if stack is empty.
Time complexity should be O(1).
4. top :
This function takes no input arguments and has return type int. This should return the last element which is entered and return that element as an answer. Return 0 if stack is empty.
Time complexity should be O(1).
5. size :
Return the size of stack i.e. count of elements which are present ins stack right now. Time complexity should be O(1).
6. isEmpty :
Checks if the stack is empty or not. Return true or false.
SOURCE CODE-
#include<iostream>
using namespace std;
class Node {
public :
int data;
Node *next;
Node(int data) {
this -> data = data;
next = NULL;
}
};
class Stack {
Node *head;
int size; // number of elements present in stack
public :
Stack() {
size=0;
head=NULL;
}
int getSize() {
return size;
}
bool isEmpty() {
return size==-1;
}
void push(int element) {
Node* current=new Node(element);
size++;
current->next=head;
head=current;
}
int pop() {
// Return 0 if stack is empty. Don't display any other message
if(head==NULL)
return 0;
size--;
int data=head->data;
head=head->next;
return data;
}
int top() {
// Return 0 if stack is empty. Don't display any other message
if(head==NULL)
return 0;
return head->data;
}
};
#include "Stack.h"
int main() {
Stack st;
int choice;
cin >> choice;
int input;
while (choice !=-1) {
if(choice == 1) {
cin >> input;
st.push(input);
}
else if(choice == 2) {
int ans = st.pop();
if(ans != 0) {
cout << ans << endl;
}
else {
cout << "-1" << endl;
}
}
else if(choice == 3) {
int ans = st.top();
if(ans != 0) {
cout << ans << endl;
}
else {
cout << "-1" << endl;
}
}
else if(choice == 4) {
cout << st.getSize() << endl;
}
else if(choice == 5) {
cout << st.isEmpty() << endl;
}
cin >> choice;
}
}
INPUT-
1 3 1 4 1 63 1 21 1 9 2 3 1 7 2 4 2 2 3 1 799 1 33 1 35 3 2 2 1 97 2 3 2 1 22 1 999 1 23 1 98 2 2 5 3 -1
OUTPUT-
9
21
7
4
21
63
4
35
35
33
97
799
799
98
23
false
999
