2010/2/12 newbiecoder <[email protected]>:
> I am having trouble mastering the concept of recursion...does anyone
> here have any advice / excellent articles to share???
>
>
> I don't understand how to create a recursion for this palindrome
> method given this format
> Palindrome(string str, int start, int end)
>
> Not sure if the code below is the proper way. It does not work if
> 'end' is an odd number....
>
>
> public static bool Palindrome(string str, int start, int end)
> {
> bool result = false;
>
> if (start == end)
>
>
> { return true; }
>
>
> else if (str[start] == str[end])
>
> { result = Palindrome(str, start + 1, end - 1); }
>
>
>
> else
> result = false;
>
>
> return result;
>
>
> }
>
Hi,
You just need to verify if end is lower than start.
It should be:
public static bool Palindrome(string str, int start, int end)
{
bool result = false;
if (start == end || end < start)
{
return true;
}
else if (str[start] == str[end])
{
result = Palindrome(str, start + 1, end - 1);
}
else
{
result = false;
}
return result;
}
Take in count that if "str.Length" is even, you will never have "start
== end". On next recursive call, end will be lower than start, and it
means it checked all chars until that point and were equals, so it's a
palindrome string (start and end intersected).
Sorry about my english. ;(
--
Oscar Mederos
