擅长:python、mysql、java
<p>如果您想跟踪调用,请添加一些打印语句:</p>
<pre><code>>>> def f(s):
... print
... print "recieved", s
... if len(s) <= 1:
... print "returning", s
... return s
... print "returning f(f(%s)) + %s" % (s[1:], s[0])
... return f(f(s[1:])) + s[0]
...
>>> print f("abcd")
recieved abcd
returning f(f(bcd)) + a
recieved bcd
returning f(f(cd)) + b
recieved cd
returning f(f(d)) + c
recieved d
returning d
recieved d
returning d
recieved dc
returning f(f(c)) + d
recieved c
returning c
recieved c
returning c
recieved cdb
returning f(f(db)) + c
recieved db
returning f(f(b)) + d
recieved b
returning b
recieved b
returning b
recieved bd
returning f(f(d)) + b
recieved d
returning d
recieved d
returning d
dbca
</code></pre>