def infix_to_postfix(expression):
operator_stack = Stack()
output = []
token_list = expression.split()
precedence = {"^": 4, "*": 3, "/": 3, "+": 2, "-": 2, "(": 1}
chars = "ABCDEFGHIJKLMNOPQRSTUVWXYZ"
for token in token_list:
try:
int(token)
number = True
except ValueError:
number = False
if token in chars or number:
output.append(token)
elif token == "(":
operator_stack.add(token)
elif token == ")":
stack_token = operator_stack.pop()
while stack_token != "(":
output.append(stack_token)
stack_token = operator_stack.pop()
else:
while (not operator_stack.is_empty()) and \
(precedence[operator_stack.peek()] >= precedence[token]):
output.append(operator_stack.pop())
operator_stack.add(token)
while not operator_stack.is_empty():
output.append(operator_stack.pop())
return " ".join(output)
def base_converter(number, base):
num_stack = Stack()
values = "0123456789ABCDEFGHIJKLMOPQ"
while number > 0:
num_stack.add(number % base)
number = number // base
converted_number = ""
while not num_stack.is_empty():
converted_number += values[num_stack.pop()]
return converted_number
class SortedStack(Stack):
def __init__(self):
super().__init__()
self._temp = Stack()
def push(self, value):
if not self.is_empty():
while not self.is_empty() and self.peek() < value:
self._temp.push(self.pop())
super().push(value)
self._unload_temp()
def _unload_temp(self):
while not self._temp.is_empty():
super().push(self._temp.pop())