import java.util.*;
class Main {
public static void main(String[] args) {
System.out.println(findPermutation(new int[]{1,2,3}));
}
public static List<List<Integer>> findPermutation(int[] input) {
List<List<Integer>> result = new ArrayList<>();
if (input == null || input.length == 0) return new ArrayList<>();
dfsWithBacktrack(input, result, new ArrayList<>());
return result;
}
private static void dfsWithBacktrack(int[] input, List<List<Integer>> result, List<Integer> level) {
//Base case
if (level.size() == input.length) result.add(new ArrayList<>(level));
for (int neighbor : input) {
if (level.contains(neighbor)) continue;
//Backtracking
level.add(neighbor);
dfsWithBacktrack(input, result, level);
level.remove(level.size() - 1);
}
}
}
