def parchecker(symbol_string):
s = Stack()
for symbol in symbol_string:
if symbol == '(':
s.push(symbol)
elif symbol == ')':
if s.isEmpty():
return False
else:
s.pop()
return s.isEmpty()
def postfixEval(expr):
operandstack = Stack()
token_list = expr.split()
for token in token_list:
if token.isnumeric():
operandstack.push(int(token))
else:
op2 = operandstack.pop()
op1 = operandstack.pop()
result = do_math(token, op1, op2)
operandstack.push(result)
return operandstack.pop()
def par_checker_v1(symbol_string):
s = Stack()
balance = True
for symbol in symbol_string:
if symbol == '(':
s.push(symbol)
else:
if s.is_empty():
balance = False
break
s.pop()
return balance and s.is_empty()
def symbol_balance_checker(symbol_string):
s = Stack()
for symbol in symbol_string:
if symbol in "{[(":
s.push(symbol)
elif symbol in "}])":
if s.isEmpty():
return False
if "{[(".index(s.pop()) != "}])".index(symbol):
return False
return s.isEmpty()
def postfix_eval(postfixexpr):
operate = {
'+': operator.add,
'-': operator.sub,
'*': operator.mul,
'/': operator.truediv
}
operand_stack = Stack()
for token in postfixexpr:
if token in '+-*/':
b = int(operand_stack.pop())
a = int(operand_stack.pop())
operand_stack.push(operate[token](a, b))
else:
operand_stack.push(token)
return operand_stack.pop()
def toStr(n, base):
convertString = "0123456789ABCDEF"
remstack = Stack()
while n > 0:
remstack.push(convertString[n % base])
n = n // base
restr = ""
while not remstack.isEmpty():
restr += remstack.pop()
return restr
def divideBy2(decNumber):
remstack = Stack()
while decNumber > 0:
rem = decNumber % 2
remstack.push(rem)
decNumber = decNumber // 2
binString = ""
while not remstack.isEmpty():
binString += str(remstack.pop())
return binString
def par_checker_v2(symbol_string):
s = Stack()
balance = True
for symbol in symbol_string:
if symbol in '([{':
s.push(symbol)
else:
if s.is_empty():
balance = False
break
top = s.pop()
if not match(top, symbol):
balance = False
break
return balance and s.is_empty()
def baseConverter(decNumber, base):
remstack = Stack()
digits = "0123456789ABCDEF"
while decNumber > 0:
rem = decNumber % base
remstack.push(rem)
decNumber = decNumber // base
newString = ""
while not remstack.isEmpty():
newString += digits[remstack.pop()]
return newString
def divide_by2(dec_number, base):
digits = '0123456789ABCDEF'
stack = Stack()
while dec_number != 0:
rem = dec_number % base
dec_number //= base
stack.push(digits[rem])
bin_string = ''
while not stack.is_empty():
bin_string += str(stack.pop())
return bin_string
def infix_to_postfix(infixexpr):
prec = {'*': 3, '/': 3, '+': 2, '-': 2, '(': 1}
postfixexpr = ''
op_stack = Stack()
for token in infixexpr:
if token in 'ABCDEFGHIJKLMNOPQRSTUWXYZ' or token in '0123456789':
postfixexpr += token
elif token == '(':
op_stack.push(token)
elif token == ')':
while not op_stack.is_empty():
op = op_stack.pop()
if op == '(':
break
postfixexpr += op
else:
while not op_stack.is_empty():
op = op_stack.peek()
if prec[op] >= prec[token]:
postfixexpr += op_stack.pop()
else:
break
op_stack.push(token)
while not op_stack.is_empty():
postfixexpr += op_stack.pop()
return postfixexpr
def infix2postfix(infixexpr):
prec = {}
prec['('] = 0
prec['+'] = prec['-'] = 1
prec['*'] = prec['/'] = 2
opstack = Stack()
postfix_list = []
for token in infixexpr:
if token.isalnum():
postfix_list.append(token)
elif token == '(':
opstack.push('(')
elif token == ')':
topToken = opstack.pop()
while topToken != '(':
postfix_list.append(topToken)
topToken = opstack.pop()
else: # is operator
while (not opstack.isEmpty()) and \
(prec[token] <= prec[opstack.peek()]):
postfix_list.append(opstack.pop())
opstack.push(token)
while not opstack.isEmpty():
postfix_list.append(opstack.pop())
return " ".join(postfix_list)
import sys
sys.path.append("..")
from pythonds.stack import Stack
s = Stack()
print(s.isEmpty())
s.push(4)
s.push('dog')
print(s.peek())
s.push(True)
print(s.size())
print(s.isEmpty())
s.push(8.4)
print(s.pop())
print(s.pop())
print(s.size())