def postfixEval(postfixExpr):
operandStack = Stack()
tokenList = postfixExpr.split()
for token in tokenList:
if token in "0123456789":
operandStack.push(int(token))
else:
operand2 = operandStack.pop()
operand1 = operandStack.pop()
result = doMath(token, operand1, operand2)
operandStack.push(result)
return operandStack.pop()
def baseConverter(decNumber, base):
digits = "0123456789ABCDEF"
remstack = Stack()
while decNumber > 0:
rem = decNumber % base
remstack.push(rem)
decNumber = decNumber // base
newString = ""
while not remstack.isEmpty():
newString += digits[remstack.pop()]
return newString
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 parChecker(symbolString):
s = Stack()
balanced = True
index = 0
while index < len(symbolString) and balanced:
symbol = symbolString[index]
if symbol == "(":
s.push(symbol)
else:
if s.isEmpty():
balanced = False
else:
s.pop()
index += 1
if balanced and s.isEmpty():
return True
else:
return False
def parChecker(symbolString):
s = Stack()
balanced = True
index = 0
while index < len(symbolString) and balanced:
symbol = symbolString[index]
if symbol in "([{":
s.push(symbol)
else:
if s.isEmpty():
balanced = False
else:
top = s.pop()
if not matches(top, symbol):
balanced = False
index += 1
if balanced and s.isEmpty():
return True
else:
return False
def infixToPostfix(infixexpr):
prec = {}
prec["*"] = 3
prec["/"] = 3
prec["+"] = 2
prec["-"] = 2
prec["("] = 1
opStack = Stack()
postfixList = []
tokenList = infixexpr.split()
for token in tokenList:
if token in string.ascii_uppercase:
postfixList.append(token)
elif token == "(":
opStack.push(token)
elif token == ")":
topToken = opStack.pop()
while topToken != "(":
postfixList.append(topToken)
topToken = opStack.pop()
else:
while (not opStack.isEmpty()) and (prec[opStack.peek()] >=
prec[token]):
postfixList.append(opStack.pop())
opStack.push(token)
while not opStack.isEmpty():
postfixList.append(opStack.pop())
return " ".join(postfixList)
LIB_PATH = '../ch_03'
sys.path.append(LIB_PATH)
from basic_functions import Stack
def toStr(n, base):
convertString = "0123456789ABCDEF"
if n < base:
return convertString[n]
else:
return toStr(n // base, base) + convertString[n % base]
def toStrStack(n, base, stack_history):
convertString = "0123456789ABCDEF"
if n < base:
rStack.push(convertString[n])
else:
rStack.push(convertString[n % base])
toStrStack(n // base, base, stack_history)
if __name__ == '__main__':
print(toStr(10, 2))
rStack = Stack()
toStrStack(10, 2, rStack)
while rStack.isEmpty() != True:
print(rStack.pop(), end='')
print()
# print(rStack)