def par_checker(symbol_string):
s = Stack()
for symbol in symbol_string:
if symbol == "(":
s.push(symbol)
else:
if s.is_empty():
return False
else:
s.pop()
return s.is_empty()
def revstring(mystr):
s = Stack()
for c in mystr:
s.push(c)
revstr = ""
while not s.is_empty():
revstr += s.pop()
return revstr
def divide_by_2(dec):
s = Stack()
while dec > 0:
rem = dec % 2
s.push(rem)
dec = dec // 2
bin = ""
while not s.is_empty():
bin += str(s.pop())
return bin
def base_converter(decimal_num, base):
s = Stack()
digits = "0123456789ABCDEF"
while decimal_num > 0:
rem = decimal_num % base
s.push(rem)
decimal_num = decimal_num // base
new_str = ""
while not s.is_empty():
new_str += digits[s.pop()]
return new_str
def to_str(n, base):
r_stack = Stack()
convert_string = "0123456789ABCDEF"
while n > 0:
if n < base:
r_stack.push(convert_string[n])
else:
r_stack.push(convert_string[n % base])
n = n // base
res = ""
while not r_stack.is_empty():
res = res + str(r_stack.pop())
return res
def infix_to_postfix(infix_expr):
prec = {"^": 4, "*": 3, "/": 3, "+": 2, "-": 2, "(": 1}
op_stack = Stack()
postfix_list = []
token_list = infix_expr.split()
for token in token_list:
if token in "ABCDEFGHIJKLMNOPQRSTUVWXYZ" or token in "0123456789":
postfix_list.append(token)
elif token == "(":
op_stack.push(token)
elif token == ")":
top_token = op_stack.pop()
while top_token != "(":
postfix_list.append(top_token)
top_token = op_stack.pop()
else:
while (not op_stack.is_empty()) and (prec[op_stack.peek()] >= prec[token]):
postfix_list.append(op_stack.pop())
op_stack.push(token)
while not op_stack.is_empty():
postfix_list.append(op_stack.pop())
return " ".join(postfix_list)