PYTHON ONLY! PLEASE FOLLOW DIRECTIONS! DIRECTIONS: import sys import stdio from

Question

PYTHON ONLY! PLEASE FOLLOW DIRECTIONS!

DIRECTIONS:

import sys
import stdio
from linkedstack import Stack

# Reads in a string as command-line argument and writes True if its
# parentheses are properly balanced and False otherwise.
def main():
# Read a string s as command-line argument.
...

# Build a stack.
...

# Define a variable balanced and set it to True.
...

# Enumerate the characters c in s. If c is any of the opening parenthesis,
# push it onto the stack. Otherwise, set balanced to False and break
# the loop if either the stack is empty or if the value atop the stack
# doesn't open c.
for c in s:
...

# The parentheses in s are balanced if balanced is True and the stack
# is empty.
...

if __name__ == '__main__':
main()

Problem 2. (Balanced Parentheses) Write a stack client Parentheses.py that reads a string as command-line argument and writes True if its parentheses are properly balanced and False otherwise. You may assume that the input string only contains parentheses. python parentheses py CO]{ CC) True python parentheses py C (J) False

Explanation / Answer

Please find my implementation:

import sys
import stdio
from linkedstack import Stack

# Reads in a string as command-line argument and writes True if its
# parentheses are properly balanced and False otherwise.
def main():
# Read a string s as command-line argument.
s = sys.argv

# Build a stack.
stack = []
# Define a variable balanced and set it to True.
isBalanced = True
pushChars, popChars = "<({[", ">)}]"
# Enumerate the characters c in s. If c is any of the opening parenthesis,
# push it onto the stack. Otherwise, set balanced to False and break
# the loop if either the stack is empty or if the value atop the stack
# doesn't open c.
for c in s :
if c in pushChars :
stack.append(c)
elif c in popChars :
if not len(stack) :
isBalanced = False
else :
stackTop = stack.pop()
balancingBracket = pushChars[popChars.index(c)]
if stackTop != balancingBracket :
isBalanced = False
else :
isBalanced = False
# The parentheses in s are balanced if balanced is True and the stack
# is empty.
if isBalanced and not len(stack):
print True
else:
print False
if __name__ == '__main__':
main()

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