# Program to implement seat reservation manager in Python

Suppose we have to design a system that manages the reservation state of n seats. The seats are numbered from 1 to n. So we have to implement the SeatReserveManager class, with these functions −

• Constructor that takes n as input and initializes the object that will manage n seats numbered from 1 to n. Initially all seats are available.

• reserve(), this will fetch the smallest-numbered unreserved seat, then reserves it, and returns its number.

• unreserve(seatNumber), this will unreserve one reserved seat with the given seatNumber.

So, if the input is like

• obj = SeatReserveManager(7)

• obj.reserve()

• obj.reserve()

• obj.reserve()

• obj.unreserve(2)

• obj.unreserve(5)

• obj.reserve()

• obj.reserve()

then the output will be 1, 2, 3, 2, 5, initially reserve three seats 1, 2, 3, then unreserved 2 and 5 but 5 is not reserved yet, then reserve 5 next.

To solve this, we will follow these steps −

• Define the Constuctor() . This will take n

• current_seat := 0

• empty_seats := a new list

• Define a function reserve() . This will take

• if length of empty_seats > 0, then

• s := minimum of empty_seats

• delete s from empty_seats

• return s

• current_seat := current_seat + 1

• return current_seat

• Define a function unreserve(). This will take seatNumber

• insert seatNumber at the end of empty_seats

## Example

Let us see the following implementation to get better understanding −

class SeatReserveManager:
def __init__(self, n):
self.current_seat = 0
self.empty_seats = []

def reserve(self):
if len(self.empty_seats) > 0:
s = min(self.empty_seats)
self.empty_seats.remove(s)
return s
self.current_seat += 1

return self.current_seat

def unreserve(self, seatNumber):
self.empty_seats.append(seatNumber)

obj = SeatReserveManager(7)
print(obj.reserve())
print(obj.reserve())
print(obj.reserve())
obj.unreserve(2)
obj.unreserve(5)
print(obj.reserve())
print(obj.reserve())

## Input

obj = SeatReserveManager(7)
print(obj.reserve())
print(obj.reserve())
print(obj.reserve())
obj.unreserve(2)
obj.unreserve(5)
print(obj.reserve())
print(obj.reserve())

## Output

1 2 3 2 5