def infixToPostfix(infixexpr):
prec = {}
prec["^"] = 3
prec["*"] = 3
prec["/"] = 3
prec["+"] = 2
prec["-"] = 2
prec["("] = 1
opStack = Stack()
postfixList = []
tokenList = infixexpr.split()
for token in tokenList:
if token in "ABCDEFGHIJKLMNOPQRSTUVWXYZ" or is_float(token):
postfixList.append(token)
elif token == '(':
opStack.push(token)
elif token == ')':
topToken = opStack.pop()
while topToken != '(':
postfixList.append(topToken)
topToken = opStack.pop()
else:
while (not opStack.isEmpty()) and \
(prec[opStack.peek()] >= prec[token]):
postfixList.append(opStack.pop())
opStack.push(token)
while not opStack.isEmpty():
postfixList.append(opStack.pop())
return " ".join(postfixList)
def merge(a, b):
sa = Stack()
sb = Stack()
# Inserir os items de cada queue em stacks independentes
for i in a.items:
sa.push(i)
for j in b.items:
sb.push(j)
# Comparar os 2 stacks
sc = Stack()
while not sa.isEmpty() and not sb.isEmpty():
if sa.peek() < sb.peek():
tmp = sa.pop()
sc.push(tmp)
tmp = sb.pop()
sc.push(tmp)
elif sb.peek() < sa.peek():
tmp = sb.pop()
sc.push(tmp)
tmp = sa.pop()
sc.push(tmp)
# Virar o stack ao contrario
sd = Stack()
while not sc.isEmpty():
tmp = sc.pop()
sd.push(tmp)
# Inserir o stack temporario na queue final
c = Queue()
for y in sd.items:
c.enqueue(y)
return c
def infixToPostfix(infixexpr):
prec = {}
prec["^"] = 3
prec["*"] = 3
prec["/"] = 3
prec["+"] = 2
prec["-"] = 2
prec["("] = 1
opStack = Stack()
postfixList = []
tokenList = infixexpr.split()
for token in tokenList:
if token in "ABCDEFGHIJKLMNOPQRSTUVWXYZ" or is_float(token):
postfixList.append(token)
elif token == '(':
opStack.push(token)
elif token == ')':
topToken = opStack.pop()
while topToken != '(':
postfixList.append(topToken)
try:
topToken = opStack.pop()
except IndexError:
return "Expressão Inválida: " + infixexpr
else:
try:
while (not opStack.isEmpty()) and (prec[opStack.peek()] >=
prec[token]):
postfixList.append(opStack.pop())
opStack.push(token)
except KeyError:
return "Operador Inválido: " + "'" + token + "'" + " de " + infixexpr
while not opStack.isEmpty():
postfixList.append(opStack.pop())
return " ".join(postfixList)