Max distance between same elements using Hashing

Problem Statement:

Given an array with repeated elements, the task is to find the maximum distance between two occurrences of an element.

Input:
The first line of input will contain no of test cases T . Then T test cases follow . Each test case contains 2 lines. The first line of each test case contains an integer N denoting the number of elements in the array, the next line contains N space separated integer's.

Output:
For each test case in new line print the Maximum distance between two occurrences of an element

Constraints:
1<=T<=100
1<=N<=1000

Example:
Input
2
6
1 1 2 2 2 1
12
3 2 1 2 1 4 5 8 6 7 4 2
Output
5
10
Explanation
Test case 1:
arr[] = {1, 1, 2, 2, 2, 1}
Max Distance: 5
Distance for 1 is: 5-0 = 5
Distance for 2 is : 4-2 = 2
Max Distance 5
Test case 2:
arr[] = {3, 2, 1, 2, 1, 4, 5, 8, 6, 7, 4, 2}
Max Distance 10
maximum distance for 2 is 11-1 = 10
maximum distance for 1 is 4-2 = 2
maximum distance for 4 is 10-5 = 5

Solution:

import java.util.Scanner;
import java.util.*;
class Max_Dis_Between_Same_Element
{
    public static void main(String args[])
    {
        Scanner sc = new Scanner(System.in);
        int t =sc.nextInt();
        while(t>0)
        {
            int n = sc.nextInt();
            int arr[] = new int[n];
            for(int i=0;i<n;i++)
                arr[i] = sc.nextInt();
            MuscleJava g = new MuscleJava();
            System.out.println(g.maxDistance(arr,n));
       
        t--;
        }
    }
}
class MuscleJava
{
    int maxDistance(int arr[], int n)
    {
        int max=0;
        HashMap<Integer,Integer> lastIndex = new HashMap<>();
        HashMap<Integer,Integer> FirstIndex = new HashMap<>();
        for(int i=0; i<n; i++)
        {
            lastIndex.put(arr[i],i);
            if(!FirstIndex.containsKey(arr[i]))
                FirstIndex.put(arr[i],i);
        }
        for(int i=0; i<n; i++)
        {
            int first = FirstIndex.get(arr[i]);
            int last = lastIndex.get(arr[i]);
            if((last - first) > max )
                max = last - first;
        }
        return max;
    }
}