Title description
给出一组数字,返回该组数字的所有排列
例如:
[1,2,3]的所有排列如下:
[1,2,3],[1,3,2],[2,1,3],[2,3,1],[3,1,2], [3,2,1].
(以数字在数组中的位置靠前为优先级,按字典序排列输出。)
Reference solution
import java.util.ArrayList;
import java.util.Arrays;
public class T_70 {
public static void main(String[] args) {
int a[] = {
1, 2, 3 };
ArrayList<ArrayList<Integer>> res = permute(a);
}
static ArrayList<ArrayList<Integer>> res;
public static ArrayList<ArrayList<Integer>> permute(int[] nums) {
res = new ArrayList<ArrayList<Integer>>();
if (nums == null || nums.length < 1)
return res;
Arrays.sort(nums);
ArrayList<Integer> list = new ArrayList<Integer>();
solve(list, nums);
return res;
}
private static void solve(ArrayList<Integer> list, int[] nums) {
if (list.size() == nums.length) {
for (int i = 0; i < list.size(); i++) {
System.out.printf("%d ", list.get(i));
}
System.out.println();
res.add(new ArrayList<Integer>(list));
return;
}
for (int i = 0; i < nums.length; i++) {
if (!list.contains(nums[i])) {
list.add(nums[i]);
solve(list, nums);
list.remove(list.size() - 1);
}
}
}
}