Try to write upDown() both recursively and without recursion. Which is easier? Why?

Question

Try writing upDown():

>>> upDown("Hello")
Hello
Hell
Hel
He
H
He
Hel
Hell
Hello

Note: Given that output, one can presume that they were either printed out, or are one string with new line characters at the end of each line.

Answer 1

Recursively:
```
def upDown(str):
print str
if len(str)>1:
upDown(str[0:len(str)-1])
print str
```

Without Recursion:
```
def upDown(str):
origStr = str
while len(str)>0:
print str
str = str[0:len(str)-1]

while len(str) str += origStr[len(str)]
print str
```

Whether you think that doing this with or without recursion is easier largely depends on your familiarity with recursion. I found the recursive version much easier as there was less code to think through.