Python Empty List of Tuples

Question

我分配的一个问题要求我编写一个函数，该函数通过使用一个wire循环的元素输入列表来迭代，然后计算到达到特定里程碑所花费的几天。我已经完成了一部分，但是如果输入列表为空，我也需要使我的函数返回None。问题是，我只允许我的代码中有一个返回语句，这就是我被卡住的地方。如何编辑代码以添加此功能？

def days_to_reach_n_steps(step_records, n):
  """DOCSTRING"""
  total_steps = 0
  counter = 0
  while total_steps < n:
      total_steps = total_steps + step_records[counter][1]
      counter = counter + 1
  return(counter) here

Answer 1

尝试此

def days_to_reach_n_steps(step_records, n):
  """DOCSTRING"""
  total_steps = 0
  counter = 0
  if len(step_records)>0:
      while total_steps < n:
          if(counter <len(step_records):
              total_steps = total_steps + step_records[counter][1]
              counter = counter + 1
          else:
              counter = "Your Message"
  return(counter if counter!=0 else None)