ใช้ Stack สองอัน (in_stack และ out_stack) จำลองพฤติกรรม Queue (FIFO)
ตัวอย่างโค้ด
class Queue_structure:
def __init__(self):
self.in_val = Stack_structure()
self.out_val = Stack_structure()
def check_empty(self):
return (self.in_val.check_empty() and self.out_val.check_empty())
def enqueue_operation(self, data):
self.in_val.push_operation(data)
def dequeue_operation(self):
if self.out_val.check_empty():
while not self.in_val.check_empty():
deleted_val = self.in_val.pop_operation()
self.out_val.push_operation(deleted_val)
return self.out_val.pop_operation()
class Stack_structure:
def __init__(self):
self.items = []
def check_empty(self):
return self.items == []
def push_operation(self, data):
self.items.append(data)
def pop_operation(self):
return self.items.pop()
my_instance = Queue_structure()
while True:
print('enqueue ')
print('dequeue')
print('quit')
my_input = input('What operation would you like to perform ?').split()
operation = my_input[0].strip().lower()
if operation == 'enqueue':
my_instance.enqueue_operation(int(my_input[1]))
elif operation == 'dequeue':
if my_instance.check_empty():
print('The queue is empty')
else:
deleted_elem = my_instance.dequeue_operation()
print('The deleted element is : ', int(deleted_elem))
elif operation == 'quit':
break
ผลลัพธ์
enqueuedequeue quit What operation would you like to perform ?enqueue 45 enqueue dequeue quit What operation would you like to perform ?enqueue 23 enqueue dequeue quit What operation would you like to perform ?enqueue 78 enqueue dequeue quit What operation would you like to perform ?dequeue The deleted element is : 45 enqueue dequeue quit What operation would you like to perform ?quit
คำอธิบาย
- Queue_structure ใช้ Stack สองอัน: in_val (push), out_val (pop)
- enqueue: push เข้า in_stack
- dequeue: ถ้า out_stack ว่าง ย้ายข้อมูลทั้งหมดจาก in_stack ไป out_stack (กลับลำดับ) แล้ว pop
- โปรแกรมรันโหมดโต้ตอบ รับคำสั่ง enqueue, dequeue, quit
