[LeetCode] Gray Code
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 - 001 - 111 - 310 - 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.
Refer to Gray Code
public class Solution { public List
grayCode(int n) { List
list = new ArrayList<>(); List
str = help(n); for(int i=0;i
help(int n){ List
list = new ArrayList<>(); if(n==0) { list.add("0"); return list; } if(n==1){ list.add("0"); list.add("1"); return list; } List
lin = help(n-1); List
res = new ArrayList<>(); for(int i=0;i
=0;i--){ String str = "1"+lin.get(i); res.add(str); } return res; }}