您至少有两个问题。
首先,else
声明不起作用,这不是你在Ruby中如何做if else
。
其次,如果a.length < 2
是false
那么您的方法将返回nil
。 puts
返回nil
,返回nil
。
我已经添加了一些版画来展示你的代码是如何工作的,希望对大家有所帮助:
$level = 0
def divide(arr)
return arr if arr.length < 2
$level += 1
puts "Working with array #{arr}"
arr1 = divide(arr[0..arr.length/2-1])
puts "Level = #{$level} arr1 = #{arr1}"
arr2 = divide(arr[arr.length/2..arr.length])
puts "Level = #{$level} arr2 = #{arr2}"
$level -= 1
nil
end
divide([5, 2, 4, 6, 1, 7, 3, 8])
输出:
Working with array [5, 2, 4, 6, 1, 7, 3, 8]
Working with array [5, 2, 4, 6]
Working with array [5, 2]
Level = 3 arr1 = [5]
Level = 3 arr2 = [2]
Level = 3 arr1 =
Working with array [4, 6]
Level = 4 arr1 = [4]
Level = 4 arr2 = [6]
Level = 4 arr2 =
Level = 4 arr1 =
Working with array [1, 7, 3, 8]
Working with array [1, 7]
Level = 6 arr1 = [1]
Level = 6 arr2 = [7]
Level = 6 arr1 =
Working with array [3, 8]
Level = 7 arr1 = [3]
Level = 7 arr2 = [8]
Level = 7 arr2 =
Level = 7 arr2 =
人我很困惑,摆脱了现在它只是返回[8]。 –