import java.util.Arrays;
import java.util.List;
import java.util.ArrayList;
import java.util.Map;
import java.util.Set;
import java.util.TreeMap;
import java.util.stream.Collectors;
class Main {
public static void main(String[] args) {
/**
* Given an array of strings strs, group the anagrams together.
*
* Input: strs = ["eat","tea","tan","ate","nat","bat"]
* Output: [["bat"],["nat","tan"],["ate","eat","tea"]]
*/
String[] strs = {"eat","tea","tan","ate","nat","bat"};
// Map to collect the sorted string as key and the ocurrences in the list as value
Map<String, List<String>> occurrencesGroups = new TreeMap<>();
// Iterating the original strings to check one by one
for (String str : strs) {
// Sorting string to prepare it for searching
String sortedStr = sortString(str);
// Value reference to add occurrences
List<String> occurrences = null;
// If the string has occurrences, then get the List of occurrences
// Otherwise, put the string as key and add a new list to add new
// occurrences
if (occurrencesGroups.containsKey(sortedStr)) {
occurrences = occurrencesGroups.get(sortedStr);
} else {
occurrences = new ArrayList<String>();
occurrencesGroups.put(sortedStr, occurrences);
}
// Adding occurrence to the reference list
occurrences.add(str);
}
// Collecting values to match expected output format
List<List<String>> occurrencesList = new ArrayList<>(occurrencesGroups.values());
System.out.println(occurrencesList);
}
private static String sortString(String str) {
return Arrays.stream(str.split(""))
.sorted()
.collect(Collectors.joining());
}
}
