def conv2hex(decD, dec_string):
"""
This will take in a decimal value in integer form and convert and return
its hexadecimal value.
"""
value = dec_string
new_stack = stack.getStack()
while (value % 16) != 0:
stack.push(new_stack, decD[value % 16])
value //= 16
final = ''
while stack.isEmpty(new_stack) == False:
final += str(stack.pop(new_stack))
return final
def main():
import stack
mystack = stack.getStack()
for item in range(1, 5):
stack.push(mystack, item)
print('Pushing', item, 'on stack')
peek = stack.peek(
mystack,
(int(input('Enter an element you want to peek into the stack: '))))
if peek == True:
print('Element is in stack')
else:
print('Element is not in stack')
while not stack.isEmpty(mystack):
item = stack.pop(mystack)
print('Popping', item, 'from stack')
def palindromeChecker(s):
""" Returns True if the provided string is a palindrome.
Uses the stack Module (added in this directory) and the Let's Apply it section from the chapter.
"""
import stack
# init
char_stack = stack.getStack()
while s != '':
if len(s) == 1:
return True
else:
# init
is_palindrome = True
# to handle strings of odd length
compare_length = len(s) // 2
# push second half of input string on stack
for k in range(compare_length, len(s)):
stack.push(char_stack, s[k])
# pop chars and compare to first half of string
k = 0
while k < compare_length and is_palindrome:
ch = stack.pop(char_stack)
if s[k].lower() != ch.lower():
is_palindrome = False
k = k + 1
# return values
if is_palindrome:
return True
else:
return False
# import stack
import stack
# define RPN_stack
RPN_stack = stack.getStack()
while True:
# user input
RPN = input("Enter an RPN expression: ")
# when user input 'q', program quits
if RPN == 'q':
break
RPN_list = RPN.split()
state = "Progress"
i = 0
num1 = 0
num2 = 0
result = 0
equal_flag = False
# push the number to the stack
while state == "Progress" and i < len(RPN_list):
if RPN_list[i] == '+' or RPN_list[i] == '*' or RPN_list[
i] == '-' or RPN_list[i] == '/' or RPN_list[i] == '=':
if RPN_list[i] == '=':
equal_flag = True
if len(RPN_stack) == 1 and i == len(RPN_list) - 1:
result = float(stack.pop(RPN_stack))
else:
inp = input('Enter an RPN expression: ')
if inp == 'q': #quit program
more = False
elif inp == '':
print('Evaluation error')
sys.exit(1)
else:
#split list by ' '
inp_list = inp.split()
#convert operands into float
for i in range(len(inp_list)):
if not is_Operator(inp_list[i]):
inp_list[i] = float(inp_list[i])
#make stack
s = stack.getStack()
#intialize evaluation result variable
evaluation = 0
#evaluate expression
for c in inp_list:
#is an operator
if is_Operator(c):
if c == '=':
evaluation = stack.pop(s)
if evaluation == None: #stack is empty
print('Evaluation error')
sys.exit(1) #exit program
elif c == '*':
o2 = stack.pop(s)
# Repeat Infinitely
while True:
# Init
# get user input
ans = input('Enter an RPN expression:')
# terminate if ans is 'q'
if ans == 'q':
sys.exit()
# split ans into list and assign itself
ans = ans.split()
# generate mainStack
mainStack = stack.getStack()
# Pre Malformed Detection
# there should exist a unique '=' at the right-most position of the statement
if ans.count('=') != 1: # not having one or having more than one
# "=" not in right-most position
terminate()
if ans[-1] != '=': # has one but not at the right-most position
# "=" not in right-most position
terminate()
# iterate ans
for item in ans:
# when item is an operator(excluding '=')
if item in ['+', '-', '*', '/']:
# detect stack underflow: need at least two operands for an operator.
# Program for Determining Palindromes
import stack
# welcome
print ('This program can determine if a given string is a palindrome\n')
print ('(Enter return to exit)')
# init
char_stack = stack.getStack()
empty_string = ''
# get string from user
chars = input('Enter string to check: ')
while chars != empty_string:
if len(chars) == 1:
print('A one letter word is by definition a palindrome\n')
else:
# init
is_palindrome = True
# determine half of length. excluding any middle character
compare_length = len(chars) // 2
# push second half of input string on stack
for k in range(compare_length, len(chars)):
stack.push(char_stack, chars[k])
# pop chars and compare to first half of string
k = 0
import stack
import sys
stk = stack.getStack()
lst = list(input('Enter parentheses and/or braces: '))
for k in range(len(lst)):
if lst[k] == '(':
stack.push(stk, lst[k])
elif lst[k] == '{':
stack.push(stk, lst[k])
elif lst[k] == ')':
if stack.isEmpty(stk):
print('Not properly nested.')
sys.exit()
if stack.pop(stk) != '(':
print('Not properly nested.')
sys.exit()
elif lst[k] == '}':
if stack.isEmpty(stk):
print('Not properly nested.')
sys.exit()
if stack.pop(stk) != '{':
print('Not properly nested.')
sys.exit()
if stack.isEmpty(stk):
print('Nested properly.')
else:
print('Not properly nested.')
import stack
mystack = stack.getStack()
for item in range(1, 5):
stack.push(mystack, item)
print('Pushing', item, 'on stack')
while not stack.isEmpty(mystack):
item = stack.pop(mystack)
print('Popping', item, 'from stack')
import stack
""" Ask the user to enter a series of braces and parentheses,
then indicate if they are properly nested
"""
char = input('Enter parentheses and/or braces: ')
sequence = stack.getStack()
#for every element in the received string checks the type and pushes/pops in/from the stack
for el in char:
if el == '(' or el == '{':
stack.push(sequence, el)
elif not stack.isEmpty(sequence):
if el == ')' and stack.top(sequence) == '(':
stack.pop(sequence)
elif el == '}' and stack.top(sequence) == '{':
stack.pop(sequence)
#Final check if the stack is empty
#If it's empty the string is proper
if stack.isEmpty(sequence):
print('Nested properly.')
else:
print('Not properly nested.')
# import stack module
import stack
# user input
pa = input("Enter parentheses and/or braces: ")
# define pa_stack
pa_stack = stack.getStack()
for i in range(0, len(pa)):
# when character is left parentheses or braces push to the stack
if pa[i] == "(" or pa[i] == "{":
stack.push(pa_stack, pa[i])
# when character is right parentheses or braces pop the stack
# if the value of the stack for top is left parentheses or braces
else:
if stack.top(pa_stack) == "(" and pa[i] == ")":
stack.pop(pa_stack)
elif stack.top(pa_stack) == "{" and pa[i] == "}":
stack.pop(pa_stack)
# output "Nested properly." when stack is empty
if stack.isEmpty(pa_stack):
print("Nested properly.")
else:
print("Not properly nested.")
result = multipl(a,b)
stack.push(numbers, result)
elif element == '/':
result = division(a,b)
stack.push(numbers, result)
""" Main functionality of the program.
Asks user to enter a sequence of
operands and operators.
Determines to which group it belongs
and do the calculation.
"""
num = stack.getStack()
while flag == True:
exp = input('Enter an RPN expression: ')
for el in exp:
if el in operand:
stack.push(num, el)
elif el in operator:
calculator(el, num)
elif el == '=':
print('Value of expression: ', int(stack.pop(num)))
else:
flag = False
#Resets the stack
num = stack.getStack()
operator = ('+', '-', '*', '/')
inp = str(input('Enter an RPN expression: '))
# About if input means terminating this program
while inp and not (inp not in '0123456789+-*/=' and len(inp) == 1):
# If not oper
for i in inp:
if i not in '0123456789+-*/= ':
termination()
right_most_position = True
oper_stack = stack.getStack()
slot = inp.split()
for item in slot:
if not right_most_position:
# print('right-most position')
termination()
if item in operator:
operand_last = stack.pop(oper_stack)
operand_second_last = stack.pop(oper_stack)
if operand_second_last == None:
# print('stack underflow')
termination()
result = multipl(a, b)
stack.push(numbers, result)
elif element == '/':
result = division(a, b)
stack.push(numbers, result)
""" Main functionality of the program.
Asks user to enter a sequence of
operands and operators.
Determines to which group it belongs
and do the calculation.
"""
num = stack.getStack()
while flag == True:
exp = input('Enter an RPN expression: ')
for el in exp:
if el in operand:
stack.push(num, el)
elif el in operator:
calculator(el, num)
elif el == '=':
print('Value of expression: ', int(stack.pop(num)))
else:
flag = False
#Resets the stack
num = stack.getStack()
import stack
""" Ask the user to enter a series of braces and parentheses,
then indicate if they are properly nested
"""
char = input('Enter parentheses and/or braces: ')
sequence = stack.getStack()
#for every element in the received string checks the type and pushes/pops in/from the stack
for el in char:
if el == '(' or el == '{':
stack.push(sequence, el)
elif not stack.isEmpty(sequence):
if el == ')' and stack.top(sequence) == '(':
stack.pop(sequence)
elif el == '}' and stack.top(sequence) == '{':
stack.pop(sequence)
#Final check if the stack is empty
#If it's empty the string is proper
if stack.isEmpty(sequence):
print('Nested properly.')
else:
print('Not properly nested.')