Interview Question for Software Engineer at Facebook:

import java.util.ArrayList;
import java.util.HashMap;

public class Solution {
    public ArrayList<Integer> findStartIndex(String S, String[] L) {
        int len = L[0].length();

        ArrayList<Integer> ret = new ArrayList<Integer>();
        HashMap<String, Integer> count = new HashMap<String, Integer>();
        HashMap<String, Integer> found = new HashMap<String, Integer>();

        for (String word : L) {
            if (!count.containsKey(word)) {
                count.put(word, 1);
            } else {
                count.put(word, count.get(word) + 1);
            }
        }

        loop: for (int i = 0; i <= S.length() - len * L.length; i++) {
            String sub = S.substring(i, i + len);
            if (!count.containsKey(sub)) {
                continue;
            }

            found.clear();
            found.put(sub, 1);

            for (int j = 1; j < L.length; j++) {
                String next_sub = S.substring(i + len * j, i + len * (j + 1));

                if (!count.containsKey(next_sub)) {
                    continue loop;
                }

                Integer foundVal = !found.containsKey(next_sub) ? 1 : found.get(next_sub) + 1;

                if (foundVal > count.get(next_sub)) {
                    continue loop;
                }

                found.put(next_sub, foundVal);
            }

            ret.add(i);
        }

        return ret;
    }
}