def is_matched_html(raw):
"""Return True if all HTML tags are properly matched;
False Otherwise."""
S = ArrayStack()
# find first '<' character
start = raw.find('<')
while start != -1:
# find next '>' character
end = raw.find('>', start + 1)
if end == -1:
return False
# strip away < >
tag = raw[start + 1:end]
# this is opening tag
if not tag.startswith('/'):
S.push(tag)
# this is closing tag
else:
if S.is_empty():
return False
if tag[1:] != S.pop():
return False
start = raw.find('<', end + 1)
# all tags matched
return S.is_empty()
def is_match(expr):
"""Return True if all the delimiters are properly matched; False Otherwise;"""
lefty = '({['
righty = ')}]'
stack = ArrayStack()
for c in expression:
if c in lefty:
stack.push(c)
elif c in righty:
if stack.is_empty():
return False
if righty.index(c) != lefty.index(stack.pop()):
return False
return stack.is_empty()
def is_matched(expr):
"""Return True if all delimiters properly match (or closed); False otherwise"""
left_delimiters = "({["
right_delimiter = ")}]"
S = ArrayStack()
for c in expr:
if c in left_delimiters:
S.push(c)
elif c in right_delimiter:
if S.is_empty():
return False
if right_delimiter.index(c) != left_delimiters.index(S.pop()):
return False
return S.is_empty()
def is_matched(expression):
"""Return True if all delimiters are properly match.
False otherwise"""
lefty = '({['
righty = ')}]'
S = ArrayStack()
for char in expression:
if char in lefty:
S.push(char)
elif char in righty:
if S.is_empty():
return False
if righty.index(char) != lefty.index(S.pop()):
return False
return S.is_empty()
def is_matched(expr):
"""Return True if all delimiters are properly matched"""
lefty ='({[' # opening delimiters
righty = ')}]' # closing delimiters
s = ArrayStack()
for c in expr:
if c in lefty:
s.push(c) # push delimiter onto the stack
elif c in righty:
if s.is_empty():
return False # nothing to match with
if righty.index(c) != lefty.index(s.pop()):
return False # mismatched
return s.is_empty() # were all symbols matched?
def is_match(raw):
stack = ArrayStack()
j = raw.find('<')
while j != -1:
k = raw.find('>', j + 1)
if k == -1:
return False
tag = raw[j + 1:k]
if not tag.startswith('/'):
stack.push(tag)
else:
if stack.is_empty():
return False
if tag[1:] != stack.pop():
return False
j = raw.find('<', k + 1)
return stack.is_empty()
def test_stack():
S = ArrayStack()
S.push(5)
print(S.top())
S.push(6)
print(len(S))
print(S.pop())
print(S.is_empty())
print(S.data)
def is_matched(expr):
"""
Return True if all delimiters are properly mathc;
False otherwise.
"""
lefty = '({[' # opening delimiters
righty = ')}]' # respective closing delims
S = ArrayStack()
for c in expr:
if c in lefty:
S.push(c) # push left delimiter on stack
elif c in righty:
if S.is_empty():
return False # nothing to match with
if righty.index(c) != lefty.index(S.pop()):
return False # mismatched
return S.is_empty() # were all symbols matched?
def is_matched_html(raw):
"""
False otherwise.
"""
S = ArrayStack()
j = raw.find('<') # find first '<' character (if any)
while j != -1:
k = raw.find('>', j + 1) # find next '>' character
if k == -1:
return False # invalid tag
tag = raw[j + 1:k] # strip away < >
if not tag.startswith('/'): # this is opening tag
S.push(tag)
else:
if S.is_empty():
return False # nothing to match with
if tag[1:] != S.pop():
return False # mismatched delimiter
j = raw.find('<', k + 1) # find next '<' character (if any)
return S.is_empty() # were all opening tags mathced?
def reverse_file(filename):
"""Overwrite a given file with contents line-by-line in reversed order"""
S = ArrayStack()
original = open(filename)
for line in original:
S.push(line.rstrip('\n')) # we will re-insert newlines while writing
original.close()
# now write the contents in LIFO order
output = open(filename, 'w')
while not S.is_empty():
output.write(S.pop() + '\n') # add trailing new line
output.close()
def is_matched_html(raw_html: str):
"""Returns True if all HTML tags are properly matched; False otherwise"""
S = ArrayStack()
j = raw_html.find("<") # find first '<' char (if any)
while j != -1: # find() returns -1 if it fails
k = raw_html.find(">", j + 1) # find next '>' char if any
if k == -1:
return False
tag = raw_html[j + 1:k] # remove '<>'
if not tag.startswith('/'): # opening tag
S.push(tag)
else: # closing tag
if S.is_empty():
return False # nothing to match with
if tag[1:] != S.pop(
): # remove '/' from closing tag and match with opening tag stored in stack
return False
j = raw_html.find('<', k +
1) # find the next '<' char (if any) for next tag
return S.is_empty(
) # were all tags were matched, then stack should be empty?
def reverse_file(filename):
"""
Overwrite given file with its contents line-by-line reversed.
"""
S = ArrayStack()
original = open(filename)
for line in original:
S.push(line.rstrip('\n')) # we will re-insert newlines when writing
original.close()
# now we over write with contents in LIFO order
output = open(filename, 'w') # reopening file overwrites orignal
while not S.is_empty():
output.write(S.pop() + '\n') # re-insert newline characters
output.close()
from arraystack import ArrayStack
# sample usage
if __name__ == '__main__':
mystack = ArrayStack()
print(mystack.is_empty())
mystack.push('hello')
mystack.push(7)
print(mystack.__len__())
print(mystack.pop())
