leetcode 089 Gray Code

最新推荐文章于 2019-09-20 21:04:01 发布

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本文介绍了一种递归方法来生成灰码序列。灰码是一种二进制数系统，其中两个连续数值只有一位不同。文中给出的示例展示了当位数为2时的灰码序列，并提供了一个C++实现方案。

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:

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.

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class Solution {
public:
	vector<int> grayCode(int n) {
		if(n==0) {
			vector<int> ret;
			ret.push_back(0);
			return ret;
		}

		vector last=grayCode(n-1);

		vector<int> ret(last);

		for(int i=(int)ret.size()-1; i>=0; i--) {
			ret.push_back(ret[i]+pow(2,n-1));
		}

		return ret;
	};
}