python - 选择最大的奇数python

Question

我正在尝试用 Python 编写一个简单的程序来计算值 x、y、z 中的最大奇数。如何让用户选择 x、y 和 z 的值？

所以程序会询问 x、y 和 z 是什么，然后说“x、y、z 是最大的奇数”或者这些数字都是偶数。

我目前所拥有的如下。这至少是一个不错的开始吗？

  # This program exmamines variables x, y, and z 
  # and prints the largest odd number among them

  if x%2 !== 0 and x > y and y > z:
      print 'x is the largest odd among x, y, and z'
  elif y%2 !== 0 and y > z and z > x:
     print 'y is the largest odd among x, y, and z'
  elif z%2 !== 0 and z > y and y > x:
     print 'z is the largest odd among x, y, and z'
  elif x%2 == 0 or y%2 == 0 or z%2 == 0:
     print 'even'

有了 thkang post，我现在有:

  # This program exmamines variables x, y, and z 
  # and prints the largest odd number among them

  if x%2 !== 0:
    if y%2 !== 0:
      if z%2 !== 0:
        if x > y and x > z: #x is the biggest odd
        elif y > z and y > x: #y is the biggest odd
        elif z > x and z > y: #z is the biggest odd

      else: #z is even
        if x > y: #x is the biggest odd
        else: #y is the biggest odd

    else: #y is even
      if z%2 != 0: #z is odd
        if x > z: #x is the biggest odd
        else: #z is the biggest odd
      else: #y,z are even and x is the biggest odd

  else: #x is even
    if y%2 != 0 and z%2 != 0; #y,z is odd
      if y > z: #y is the biggest odd
      else: #z is the biggest odd
    else: #x and y is even
      if z%2 != 0: #z is the biggest odd

Answer 1

方法

避免使用 if-stmts 来查找最大值。使用 python 内置 max。使用生成器或 filter 仅查找奇数。

像这样使用内置函数更安全/更可靠，因为它们的组合更简单，代码经过良好测试，并且代码主要在 C 中执行(而不是多字节代码指令)。

代码

def find_largest_odd(*args):
    return max(arg for arg in args if arg & 1)

或:

def find_largest_odd(*args):
    return max(filter(lambda x: x & 1, args))

测试

>>> def find_largest_odd(*args):
...     return max(arg for arg in args if arg & 1)
... 
>>> print find_largest_odd(1, 3, 5, 7)
7
>>> print find_largest_odd(1, 2, 4, 6)
1

和:

>>> def find_largest_odd(*args):
...     return max(filter(lambda x: x & 1, args))
>>> print find_largest_odd(1, 3, 5, 7)
7
>>> print find_largest_odd(1, 2, 4, 6)
1

如果您传递一个空序列或仅提供偶数，您将得到一个ValueError:

>>> find_largest_odd(0)
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "<stdin>", line 2, in find_largest_odd
ValueError: max() arg is an empty sequence

引用资料

• filter
• max
• generators