递归

 

public class Recursion {
	public static void main(String[] args) {
		int[] nums = { 1, 2, 3 };
		Recursion recursion = new Recursion();
		List<List<Integer>> permute = recursion.permute(nums);
		System.out.println(permute.toString());
	}
	public List<List<Integer>> permute(int[] nums) {
		List<List<Integer>> list = new ArrayList<>();
		swap(list, nums, 0);

		return list;
	}

	public List<Integer> swap(List<List<Integer>> list, int[] nums, int k) {
		if (k >= nums.length - 1) {
			List<Integer> miniList = new ArrayList<>();
			for (int i = 0; i < nums.length; i++) {
				miniList.add(nums[i]);
			}
			list.add(miniList);
			return null;
		}
		for (int i = k; i < nums.length; i++) {
			int temp = nums[i];
			nums[i] = nums[k];
			nums[k] = temp;
			swap(list, nums, k + 1);
			temp = nums[i];
			nums[i] = nums[k];
			nums[k] = temp;
		}

		return null;
	}
}

 

 

 

36

 

 

 

1

public class Recursion {

2

public static void main(String[] args) {

3

int[] nums = { 1, 2, 3 };

4

Recursion recursion = new Recursion();

5

List<List<Integer>> permute = recursion.permute(nums);

6

System.out.println(permute.toString());

7

}

8

public List<List<Integer>> permute(int[] nums) {

9

List<List<Integer>> list = new ArrayList<>();

 

 

10

swap(list, nums, 0);

11

12

return list;

13

}

14

15

public List<Integer> swap(List<List<Integer>> list, int[] nums, int k) {

16

if (k >= nums.length - 1) {

17

List<Integer> miniList = new ArrayList<>();

18

for (int i = 0; i < nums.length; i++) {

19

miniList.add(nums[i]);

20

}

21

list.add(miniList);

22

return null;

23

}

24

for (int i = k; i < nums.length; i++) {

25

int temp = nums[i];

26

nums[i] = nums[k];

27

nums[k] = temp;

28

swap(list, nums, k + 1);

29

temp = nums[i];

30

nums[i] = nums[k];

31

nums[k] = temp;

32

}

33

34

return null;

35

}

36

}

 

 

 

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