Perl Regex替换除字符串中的特定域之外的所有域(Perl Regex replace all domain except a particular in a string)

 我有一个域名字符串如下： 
 
$string = 'https://code.google.com && http://mycode.com/data && times.com && https://thehindu.com';
 
 我想用mycode.com/unknown替换mycode.com以外的所有域名 
 
 所以应用正则表达式后上面字符串的输出应该是： 
 
https://mycode.com/unknown && http://mycode.com/data && mycode.com/unknown && https://mycode.com/unknown
 
 我试过下面的正则表达式，但它也改变了http://mycode.com/data ： 
 
$string =~ s/(?<!mycode)[a-z\.]+?\.(com|org|net)/mycode\.com\/unknown/g;
 
 我应该如何修改我的正则表达式以匹配mycode.com 

I have a string of domain like below:
 
$string = 'https://code.google.com && http://mycode.com/data && times.com && https://thehindu.com';
 
I want to replace all domains except mycode.com with mycode.com/unknown
 
So the output of above string after applying regex should be:
 
https://mycode.com/unknown && http://mycode.com/data && mycode.com/unknown && https://mycode.com/unknown
 
I have tried below regex, but it changes http://mycode.com/data also:
 
$string =~ s/(?<!mycode)[a-z\.]+?\.(com|org|net)/mycode\.com\/unknown/g;
 
How should i modify my regex to not match mycode.com

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