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.
此题不算难,主要是要掌握什么是格雷码,然后才能做这道题,具体格雷码概念参考百度即可,具体解法是遍历,逐一试探即可。
代码如下:
public class Solution { public List<Integer> grayCode(int n) { List<Integer> list = new ArrayList<Integer>(); //去除重复 Set<String> set = new HashSet<String>(); //表示二进制数的数组 char[] c = new char[n]; Arrays.fill(c, '0');//全部为0 set.add(new String(c)); list.add(0); int i = 1;//从1开始 //格雷码长度 int len = (int) Math.pow(2, n); while(i++ < len){ //逐个尝试 for(int j = c.length - 1; j >= 0; j--){ c[j] = c[j] == '1' ? '0':'1';//每一位均异或 String b = new String(c); //成功则添加结果集,并结束循环 if(set.add(b)){ //二进制转换为十进制 list.add(Integer.valueOf(b, 2)); break; }else{ //如果不是则数值变换回来 c[j] = c[j] == '1' ? '0':'1'; } } } return list; } }
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时间: 2024-10-25 10:10:25