Python 表达式等于结果时如何打印

我被困在这个问题上，是否有任何方法可以打印出与用户输入的结果数相等的表达式，而不是所有可能的排列

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编辑：如果你可以看到我有一个名为result的变量，现在有了所有的置换表达式，我想打印与结果相等的表达式如果你将整数转换成字符串，那么你可以将每个置换连接到字符串，你可以使用eval来计算它-即如果eval1+2+3+4==10：

编辑：对于@lbragile版本，返回

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要添加到@furas answer中，我认为以下代码语法更好：

vals = [1, 2, 3, 4]
operators = ['+', '*', '-', '/']
result = 10

def expressions(values):

    if len(values) == 1:
        return [values]  # has to return list of lists

    results = [] # create list for all lists

    for i in range(len(values)):

        forward = values[:]
        val = forward.pop(i)

        for op in operators:
            for rest in expressions(forward):
                results.append([val, op] + rest)

    return results # return all lists at once


for x in expressions(vals):
    x = ' '.join(map(str, x))
    if eval(x) == result:
        print(x, '=', eval(x))

输出：

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你能给我更多的信息吗？这个问题不清楚。请在你的文章中包含任何代码和数据，而不是图片。编辑，粘贴code@furas请问您为什么使用收益率而不是收益率？@lbragile我使用问题和OP使用收益率的代码。我甚至没有检查代码中的内容。@furas我看到了。我认为这是因为pop减少了每次递归调用的列表大小，而yield只是生成输出。我不知道为什么使用return会给出：回溯最近的调用last:File main.py，第20行，在表达式中的x中vals:File main.py，第13行，在表达式中rest的表达式中forward:File main.py，第13行，在表达式中rest的表达式中forward:File main.py，第14行，在表达式中return[val，op]+rest TypeError:只能将列表not int连接到list@lbragile对于return，您必须创建包含所有结果的列表，然后返回此列表。因为它返回列表列表，所以它还需要在返回[values]中使用[]来创建列表列表-列表中有一个列表values@lbragile我还使用return添加到了answer版本中，这将给出与结果变量相同类型的输出RHS 10，在本例中为aka integer。

vals = [1, 2, 3, 4]
operators = ['+', '*', '-', '/']
result = 10

def expressions(values):

    if len(values) == 1:
        yield values

    for i in range(len(values)):

        forward = values[:]
        val = forward.pop(i)


        for op in operators:
            for rest in expressions(forward):
                yield [val, op] + rest


for x in expressions(vals):
    x = ' '.join(map(str, x))
    if eval(x) == result:
        print(x, '=', eval(x))

vals = [1, 2, 3, 4]
operators = ['+', '*', '-', '/']
result = 10

def expressions(values):

    if len(values) == 1:
        return [values]  # has to return list of lists

    results = [] # create list for all lists

    for i in range(len(values)):

        forward = values[:]
        val = forward.pop(i)

        for op in operators:
            for rest in expressions(forward):
                results.append([val, op] + rest)

    return results # return all lists at once


for x in expressions(vals):
    x = ' '.join(map(str, x))
    if eval(x) == result:
        print(x, '=', eval(x))

def expressions(vals):
  global operators

  if len(vals) == 1:
    yield vals

  else:
    for i in range(len(vals)):
      forward = vals[:]
      val = forward.pop(i)

      for op in operators:
        for rest in expressions(forward):
          yield [val, op] + rest

vals = [1, 2, 3, 4]
operators = ['+', '*', '-', '/']
result = 10

for x in expressions(vals):
  x = ' '.join(map(str, x))
  if eval(x) == result:
    print("{} = {}".format(x, int(eval(x))))

1 + 2 + 3 + 4 = 10
1 + 2 + 4 + 3 = 10
1 + 3 + 2 + 4 = 10
1 + 3 + 4 + 2 = 10
1 + 4 + 2 + 3 = 10
1 + 4 + 3 + 2 = 10
1 * 2 * 3 + 4 = 10
1 * 3 * 2 + 4 = 10
1 * 3 * 4 - 2 = 10
1 * 4 + 2 * 3 = 10
1 * 4 + 3 * 2 = 10
1 * 4 * 3 - 2 = 10
2 + 1 + 3 + 4 = 10
2 + 1 + 4 + 3 = 10
2 + 3 + 1 + 4 = 10
2 + 3 + 4 + 1 = 10
2 + 4 + 1 + 3 = 10
2 + 4 + 3 + 1 = 10
2 * 1 * 3 + 4 = 10
2 * 3 + 1 * 4 = 10
2 * 3 + 4 * 1 = 10
2 * 3 + 4 / 1 = 10
2 * 3 * 1 + 4 = 10
2 * 3 / 1 + 4 = 10
2 * 4 + 3 - 1 = 10
2 * 4 - 1 + 3 = 10
2 / 1 * 3 + 4 = 10
3 + 1 + 2 + 4 = 10
3 + 1 + 4 + 2 = 10
3 + 2 + 1 + 4 = 10
3 + 2 + 4 + 1 = 10
3 + 2 * 4 - 1 = 10
3 + 4 + 1 + 2 = 10
3 + 4 + 2 + 1 = 10
3 + 4 * 2 - 1 = 10
3 * 1 * 2 + 4 = 10
3 * 1 * 4 - 2 = 10
3 * 2 + 1 * 4 = 10
3 * 2 + 4 * 1 = 10
3 * 2 + 4 / 1 = 10
3 * 2 * 1 + 4 = 10
3 * 2 / 1 + 4 = 10
3 * 4 * 1 - 2 = 10
3 * 4 - 1 * 2 = 10
3 * 4 - 2 * 1 = 10
3 * 4 - 2 / 1 = 10
3 * 4 / 1 - 2 = 10
3 - 1 + 2 * 4 = 10
3 - 1 + 4 * 2 = 10
3 / 1 * 2 + 4 = 10
3 / 1 * 4 - 2 = 10
4 + 1 + 2 + 3 = 10
4 + 1 + 3 + 2 = 10
4 + 1 * 2 * 3 = 10
4 + 1 * 3 * 2 = 10
4 + 2 + 1 + 3 = 10
4 + 2 + 3 + 1 = 10
4 + 2 * 1 * 3 = 10
4 + 2 * 3 * 1 = 10
4 + 2 * 3 / 1 = 10
4 + 2 / 1 * 3 = 10
4 + 3 + 1 + 2 = 10
4 + 3 + 2 + 1 = 10
4 + 3 * 1 * 2 = 10
4 + 3 * 2 * 1 = 10
4 + 3 * 2 / 1 = 10
4 + 3 / 1 * 2 = 10
4 * 1 + 2 * 3 = 10
4 * 1 + 3 * 2 = 10
4 * 1 * 3 - 2 = 10
4 * 2 + 3 - 1 = 10
4 * 2 - 1 + 3 = 10
4 * 3 * 1 - 2 = 10
4 * 3 - 1 * 2 = 10
4 * 3 - 2 * 1 = 10
4 * 3 - 2 / 1 = 10
4 * 3 / 1 - 2 = 10
4 / 1 + 2 * 3 = 10
4 / 1 + 3 * 2 = 10
4 / 1 * 3 - 2 = 10