package LeetCode;
import java.util.ArrayList;
import java.util.List;
public class Permutations {
List> lists;
int count=0;
public List> permute(int[] nums,int k) {
lists = new ArrayList>();
helper(nums, 0, nums.length, new ArrayList(),k);
return lists;
}
private void helper(int[] nums, int start, int length, List list,int k) {
if (list.size() == length) {
lists.add(new ArrayList(list));
count++;
return;
}
if (start >= length || count>k) {
return;
}
for (int i = 0; i < length; i++) {
if (list.contains(nums[i])) {
continue;
}
// Choose
list.add(nums[i]);
// Explore
helper(nums, i, length, new ArrayList(list),k);
// UnChoose
list.remove(list.size() - 1);
}
}
public static void main(String[]args){
Permutations permutations=new Permutations();
int[] nums={1,2,3,4};
System.out.println(permutations.permute(nums,3));
}
}