def cleanstack(ip):
length = 0
cleaned = ArrayStack()
while not ip.isempty:
if cleaned.top != ip.top:
cleaned.push(ip.top)
ip.pop()
length += 1
else:
ip.pop()
return cleaned, length
def test_isduplindrome_two():
ip = ArrayStack()
ip.push('m')
ip.push('a')
ip.push('d')
ip.push('a')
ip.push('m')
assert (isduplindrome(ip) == True)
def isstackpalindrome(ip, length, temp=None):
print ip.stack
if not temp:
temp = ArrayStack()
odd = False
if length % 2 != 0:
odd = True
for _ in range(0, int(length / 2)):
temp.push(ip.top)
ip.pop()
if odd:
ip.pop()
while not ip.isempty:
if ip.top != temp.top:
return False
ip.pop()
temp.pop()
return True
def test_isduplindrome_three():
ip = ArrayStack()
ip.push('m')
ip.push('a')
ip.push('d')
ip.push('m')
assert (isduplindrome(ip) == False)
def postfix_evaluation(items):
"""Evaluate Reverse Polish Notation."""
stack = ArrayStack()
op = ["+", "-", "*", "/"]
for item in items:
if item not in op:
stack.push(int(item))
else:
op2 = stack.top
stack.pop()
op1 = stack.top
stack.pop()
if item == "+":
ans = int(op1 + op2)
stack.push(ans)
elif item == "-":
ans = int(op1 - op2)
stack.push(ans)
elif item == "*":
ans = int(op1 * op2)
stack.push(ans)
elif item == "/":
ans = int(float(op1) / float(op2))
stack.push(ans)
else:
raise IOError("Invalid operator specified - {0}".format(item))
return stack.top
def prefix_evaluation(items):
"""Evaluate Prefix Notation."""
stack = ArrayStack()
op = ["+", "-", "*", "/"]
for item in reversed(items):
if item not in op:
stack.push(int(item))
else:
op1 = stack.top
stack.pop()
op2 = stack.top
stack.pop()
if item == "+":
ans = int(op1 + op2)
print "{0} + {1} = {2}".format(op1, op2, ans)
stack.push(ans)
elif item == "-":
ans = int(op1 - op2)
stack.push(ans)
elif item == "*":
ans = int(op1 * op2)
stack.push(ans)
elif item == "/":
ans = int(float(op1) / float(op2))
stack.push(ans)
else:
raise IOError("Invalid operator specified - {0}".format(item))
return stack.top