LeetCode (Gray Code)

Problem:

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.

Solution:

class Solution {public:    vector<int> grayCode(int n) {        vector<int> ans;        if(n == 0) return {0};        vector<int> temp = grayCode(n - 1);        for(int i = 0; i < temp.size(); i++){            ans.insert(ans.begin() + i, temp[i]);            ans.insert(ans.begin() + i + 1, temp[i] + pow(2, n - 1));        }        return ans;    }};