fork download

copy

//Program to reverse  queue but in O(n) and O(1) space
 
#include<conio.h>
#include<stdio.h>
#include<iostream.h>
#define MAX 7
int Q[MAX];
int f = -1, r = -1;
void display();
int rev();
int isempty();
int isfull();
int enq(int d);
int deq();
int main()
{
	int i;
	for(i=1;i<=MAX;i++)
	enq(i);
	display();
	rev();
	display();
 
 
getch();
return 0;
}
int rev()
{
	if(!isempty()) //if not empty
	{
		int temp = deq();
		rev();
		enq(temp);
	}
else return 0;
 
}
void display()
{
	int i;
	cout<<"\n";
	for(i=f;i<=r;i++)
	cout<<"  "<<Q[i];
 
}
int isempty()
{
	if((f==-1 && r==-1)) 
	return 1;
	else 
	return 0;
 
}
int isfull()
{
	if(f==r+1 || (f==0 && r==MAX-1))
	return 1;
	else
	return 0;
 
}
int enq(int d)
{
	if(isfull())
	{
		cout<<"\n Cannot insert already full - ";
		return 0;
	}
	//decide new position of r
	if(f==r && r==-1)
	{r=0;f=0;} //only 1 element
	else if(r==MAX-1)
	r=0;
	else
	r=r+1;
	Q[r] = d;
return 1;
 
}
int deq()
{
	if(isempty())
	{
	cout<<"\n Already empty - ";
	return 0;
	}
	int temp = Q[f];
	//now decide new postion of f
	if(f==r) //only one element was der
	{
		f = r = -1; //empty the queue
	}
	else if (f==MAX-1)
	f=0;
	else
	f+=1; //increment front
 
return temp;
}
 

prog.cpp:3:18: error: conio.h: No such file or directory
prog.cpp:5:21: error: iostream.h: No such file or directory
prog.cpp: In function ‘int main()’:
prog.cpp:25: error: ‘getch’ was not declared in this scope
prog.cpp: In function ‘void display()’:
prog.cpp:42: error: ‘cout’ was not declared in this scope
prog.cpp: In function ‘int enq(int)’:
prog.cpp:67: error: ‘cout’ was not declared in this scope
prog.cpp: In function ‘int deq()’:
prog.cpp:85: error: ‘cout’ was not declared in this scope

Standard output is empty