Apex Basics & Database Unit 5/5

Hello, Community, I am facing problem in solving this challenge, please advise.

Here is the criteria presented: 

With SOSL you can search against different object types that may have similar data, such as contacts and leads. To pass this challenge, create an Apex class that returns both contacts and leads that have first or last name matching the incoming parameter.

The Apex class must be called 'ContactAndLeadSearch' and be in the public scope.
The Apex class must have a public static method called 'searchContactsAndLeads'.
Because SOSL indexes data for searching, you must create a Contact record and Lead record before checking this challenge. Both records must have the last name 'Smith'. The challenge uses these records for the SOSL search.
The return type for 'searchContactsAndLeads' must be 'List<List< SObject>>'
The 'searchContactsAndLeads' method must accept an incoming string as a parameter, find any contact or lead that matches the string as part of either the first or last name and then return those records.

Error received: 
Challenge not yet complete... here's what's wrong: 
Executing the 'searchContactsAndLeads' method failed. Either the method does not exist, is not static, or does not return the expected search results.

Here is my code:
public class ContactAndLeadSearch{
    public static List<List< SObject>> searchContactsAndLead(String name)
    {
        List<List<sObject>> result=[FIND :name IN ALL FIELDS RETURNING Lead(LastName),Contact(LastName)];
                return result;
    }
}

PLEASE ADVISE...Thanks Community!!!

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.