FilesExpand file tree

 master

/

GrayCode.java

Copy path

Blame

More file actions

Blame

More file actions

Latest commit

 

History

History

History

48 lines (44 loc) · 1.15 KB

 master

/

GrayCode.java

Copy path

Top

File metadata and controls

• Code
• Blame

48 lines (44 loc) · 1.15 KB

Raw

Copy raw file

Download raw file

Open symbols panel

Edit and raw actions

1

2

3

4

5

6

7

8

9

10

11

12

13

14

15

16

17

18

19

20

21

22

23

24

25

26

27

28

29

30

31

32

33

34

35

36

37

38

39

40

41

42

43

44

45

46

47

48

import java.util.ArrayList;

/**

* The gray code is a binary numeral system where two successive values differ

* in only one bit.

*

* Given a non-negative integer n representing the total number of bits in the

* code, print the sequence of gray code. A gray code sequence must begin with 0.

*

* For example, given n = 2, return [0,1,3,2]. Its gray code sequence is:

*

* 00 - 0

* 01 - 1

* 11 - 3

* 10 - 2

*

* Note:

*

* For a given n, a gray code sequence is not uniquely defined.

*

* For example, [0,2,3,1] is also a valid gray code sequence according to the above definition.

*

* For now, the judge is able to judge based on one instance of gray code sequence. Sorry about that.

*/

public class GrayCode {

public ArrayList<Integer> grayCode(int n) {

ArrayList<Integer> result = new ArrayList<Integer>();

if (n == 0) {

result.add(0);

return result;

}

;

result.add(0);

result.add(1);

for (int i = 1; i < n; i++) {

ArrayList<Integer> tmp = new ArrayList<Integer>(result);

Integer a = 1 << i;

for (int k = result.size() - 1; k >= 0; k--) {

tmp.add(result.get(k) + a);

}

result = tmp;

}

return result;

}

}