[LeetCode] Gray Code

Gray Code My Submissions Question Solution Total Accepted: 41835

Total Submissions: 125744 Difficulty: Medium 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.

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格雷码，n=3时的格雷码wei

000

001

011

010

110

111

101

格雷码的n位保留，另外n位不动，首位添加1，再逆序添加，则可以变成n+1位的格雷码。

class Solution {
public:
vector<int> grayCode(int n) {
vector<int> vec;
vec.push_back(0);
int highbit = 0;
while(n--){
highbit = vec.size();
//倒叙添加高位1
for(int i = highbit-1; i>=0;--i)
vec.push_back(highbit|vec[i]);
}
return vec;

}
};