getting error: 
Challenge Not yet complete... here's what's wrong: 
Executing the 'generateStringArray' method failed. Either the method does not exist, is not static, or does not return the proper number of strings.


public class StringArrayTest {
    
    public static string[] generateStringArray(integer n){
        
        List<string> l1=new LIst<String>(n);
        
        for(integer j=0; j< n; j++){
            l1.add(j, 'Test '+j);
        }
        return (l1);
    }
}

I was solving this challenge and my VF code is:

<apex:page standardController="Account" recordSetVar="Accounts" >
    <apex:pageblock>
        <apex:repeat var="a" value="{!Accounts}" rendered="true"  id="account_list">
            <li>
                <apex:outputLink value="https://ap1.salesforce.com/{!a.ID}" >
                    <apex:outputText value="{!a.Name}"/>
                </apex:outputLink>
            </li>
        </apex:repeat>
    </apex:pageblock>
</apex:page>

I am getting the list of accounts as required and on clicking on any of the accouts, it redirects to that accounts detail page.
Still I am getting following error from trailhead:

"The page does not bind to the record ID value (in order to link to the record detail page)"

Create an Apex class that returns an array (or list) of strings: 
Create an Apex class that returns an array (or list) of formatted strings ('Test 0', 'Test 1', ...). The length of the array is determined by an integer parameter.The Apex class must be called 'StringArrayTest' and be in the public scope.
The Apex class must have a public static method called 'generateStringArray'.
The 'generateStringArray' method must return an array (or list) of strings. Each string must have a value in the format 'Test n' where n is the index of the current string in the array. The number of returned strings is specified by the integer parameter to the 'generateStringArray' method.

MyApexClass to above Challenge:

public class StringArrayTest {
    
    public static List<string> generateStringArray(Integer n)
    {
        List<String> myArray = new List<String>();
        
        for(Integer i=0;i<n;i++)
        {
            myArray.add('Test'+i);
            System.debug(myArray[i]);
        }
        return myArray;
        
    }

It's compile and execute as per requirement in Developer console. But Traihead showing the below error:

Challenge not yet complete... here's what's wrong: 
Executing the 'generateStringArray' method failed. Either the method does not exist, is not static, or does not return the proper number of strings.

Anyhelp would be greatly appreciated. Thanks.