Should I be using 2D arrays for this problem (or) how do I go about solving

Question

An array is being used to represent an organizational hierarchy. This is done by using the array subscript to map to the employee-id and the value in each element to represent the employee-id of the supervisor of the employee.
For example the first element in the array maps to the supervisor of employee-id 1, the second element maps to the supervisor of employee id 2. The corresponding value for the top person in the organization is set to -1.
For example the following array ?
7 5 7 10 -1 7 5 2 2 5
translates to the following hierarchical structure -
? employee 5 is the top boss
? employees 2, 7, and 10 report to employee 5
? employees 8 and 9 report to employee 2
? employees 1, 3 and 6 report to employee 7
? employee 4 reports to employee 10
The following diagram represents the organization structure
5
+ --- 2
| + --- 8
| + --- 9
|
+ --- 7
| + --- 1
| + --- 3
| + --- 6
|
+ --- 10
+ --- 4
5 is at level 1 in the organization.
2, 7 and 10 are at level 2
1, 3, 4, 6, 8, 9 are at level 3
Given an array of size N (the employee-ids being 1 to N), write a program to find the number of people in level L, where the top person in the organization is at level 1.

Answer 1

Database is overkill!
heres your assignment
package myjava.demo;
class DemoLevel{
     class LevelData{
        int members[];
        int size = 0;
        int level = 0;
        public String toString() { return "Level: " + level + " Size: " + size;}
    LevelData getNextLevel(int data[],LevelData current){
        LevelData nextlevel = new LevelData();
        nextlevel.level = current.level + 1;
        nextlevel.members = new int[data.length];
        for(int i = 0; i< data.length;i = i + 1){
            if(data[i] != -1 && current.members[data[i]-1] != 0){ //data[i] indicates i's parent. this ask if its a member of current
                nextlevel.members[i] = data[i]-1; //store its parent. not needed in this algo. but better then true and false
                nextlevel.size = nextlevel.size + 1;
            }else{ nextlevel.members[i] = 0;}
        return nextlevel;
    LevelData getFirstLevel(int data[]){
        LevelData firstlevel = new LevelData();
        firstlevel.level = 1;
        firstlevel.members = new int [data.length];
        for(int i = 0; i < data.length;i = i + 1){
            if(data[i] == -1){
                firstlevel.members[i] =   -1;
                firstlevel.size = firstlevel.size + 1;
            }else { firstlevel.members[i] = 0;}
        return firstlevel;
    void execute(){
        int data[] = { 7, 5, 7, 10, -1, 7, 5, 2, 2, 5};
        LevelData current = getFirstLevel(data);
        System.out.println(current);
        while(current.size != 0)
            current = getNextLevel(data,current);
            System.out.println(current);
public class Demo {
    public static void main(String[] args) {
        DemoLevel dl = new DemoLevel();
        dl.execute();