擅长:python、mysql、java
<p>如果不想使用<code>return</code>,可以创建<code>global</code>参数,并在函数完成后调用它以执行:</p>
<pre><code>res = []
def countStrings(n, out="", last_digit=0):
global res
# if the number becomes n–digit, print it
if n == 0:
print(out)
res.append(out)
return
# append 0 to the result and recur with one less digit
countStrings(n - 1, out + '1', 0)
# append 1 to the result and recur with one less digit
# only if the last digit is 0
if last_digit == 0:
countStrings(n - 1, out + '0', 1)
</code></pre>
<p>调用<code>print(res)</code>将为您提供:</p>
<pre><code>['111', '110', '101', '011', '010']
</code></pre>