确定的研究，如果输入的是偶数或奇数

Question

你好我试图用Python语言编写一个程序，要求用户输入一组1的数量和0的和我想要的程序来告诉我，如果我有和偶数零或奇数个零或根本不为零。谢谢你的帮助！！

forstate = "start" 
curstate = "start" 
trans = "none" 
value = 0 


print "Former state....:", forstate 
print "Transition....:", trans 
print "Current state....", curstate 
    while curstate != "You hav and even number of zeros": 
     trans = raw_input("Input a 1 or a 0: ") 
     if trans == "0" and value <2: 
      value = value + 1 
      forstate = curstate 
     elif trans == "1" and value < 2: 
      value = value + 0 
      forstate = curstate 
     curstate = str(value) + " zeros" 
     if value >= 2: 
      curstate = "You have and even number of zeros" 
     print "former state ...:", forstate 
     print "Transition .....:", trans 
     print "Current state....", curstate 

Answer 1

貌似你试图做一个有限状态机？

try: 
    inp = raw_input 
except NameError: 
    inp = input 

def getInt(msg): 
    while True: 
     try: 
      return int(inp(msg)) 
     except ValueError: 
      pass 

START, ODD, EVEN = range(3) 
state_next = [ODD, EVEN, ODD] 
state_str = ['no zeros yet', 'an odd number of zeros', 'an even number of zeros'] 

state = START 
while True: 
    num = getInt('Enter a number (-1 to exit)') 

    if num==-1: 
     break 
    elif num==0: 
     state = state_next[state] 

    print 'I have seen {0}.'.format(state_str[state]) 

编辑：

try: 
    inp = raw_input 
except NameError: 
    inp = input 

START, ODD, EVEN = range(3) 
state_next = [ODD, EVEN, ODD] 
state_str = ['no zeros yet', 'an odd number of zeros', 'an even number of zeros'] 

def reduce_fn(state, ch): 
    return state_next[state] if ch=='0' else state 

state = reduce(reduce_fn, inp('Enter at own risk: '), START) 
print "I have seen " + state_str[state] 

Answer 2

这听起来像功课，或者更糟糕的面试问题，但这会让你开始。

def homework(s): 
counter = 0 
if '0' in s: 
    for i in s: 
    if i == '0': 
     counter = counter + 1 
return counter 

不要在这里忘了这部分

def odd_or_even_or_none(num): 
    if num == 0: 
    return 'This string contains no zeros' 
    if num % 2 == 0 
    return 'This string contains an even amount of zeros' 
    else: 
    return 'This string contains an odd amount of zeros' 

如果你打电话的功课，并给它一串数字，它会给你回0

homework('101110101') 

数量现在你知道你需要多少个0调用odd_or_even_or_none与数

odd_or_even_or_none(23) 

因此该解决方案是这样的

txt = input('Feed me numbers: ') 
counter = str(homework(txt)) 
print odd_or_even_or_none(counter) 

Answer 3

try: 
    inp = raw_input 
except NameError: 
    inp = input 

zeros = sum(ch=='0' for ch in inp('Can I take your order? ')) 

if not zeros: 
    print "none" 
elif zeros%2: 
    print "odd" 
else: 
    print "even" 

Answer 4

简单的解决问题的方法就是计数为零，然后打印一个合适的消息。 num_zeros = input_stream.count('0')

如果您打算构建一个有限状态机来学习如何编写一个状态机，那么您将学习更多写一个通用FSM并使用它来解决您的特定问题。这里是我的尝试 - 注意，所有用于计算零逻辑的状态及其转换进行编码。

class FSMState(object): 
    def __init__(self, description): 
     self.transition = {} 
     self.description = description 
    def set_transitions(self, on_zero, on_one): 
     self.transition['0'] = on_zero 
     self.transition['1'] = on_one 

def run_machine(state, input_stream): 
    """Put the input_stream through the FSM given.""" 
    for x in input_stream: 
     state = state.transition[x] 
    return state 

# Create the states of the machine. 
NO_ZEROS = FSMState('No zeros') 
EVEN_ZEROS = FSMState('An even number of zeros') 
ODD_ZEROS = FSMState('An odd number of zeros') 

# Set up transitions for each state 
NO_ZEROS.set_transitions(ODD_ZEROS, NO_ZEROS) 
EVEN_ZEROS.set_transitions(ODD_ZEROS, EVEN_ZEROS) 
ODD_ZEROS.set_transitions(EVEN_ZEROS, ODD_ZEROS) 

result = run_machine(NO_ZEROS, '01011001010') 
print result.description