2.1.18Gray Code

1120 단어
Notes:
 
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.
 
 
Solution: Refer to http://en.wikipedia.org/wiki/Gray_code.
class Solution {
public:
    vector<int> grayCode(int n) {
        vector<int> result(1 << n, 0);
        for (int i = 0; i < 1 << n; ++i)
            result[i] = (i >> 1) ^ i;//     
        return result;
    }
};

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