Leetcode: Gray Code

Leetcode: Gray Code

The gray code is a binary numeral system where two successive values differ in only one bit.

Given a non-negative integerNRepresenting the total number of BITs in the code, print the sequence of Gray code. A gray code sequence must begin with 0.

For example, givenN= 2, return[0,1,3,2]. Its Gray code sequence is:

00 - 001 - 111 - 310 - 2

Note:
For a givenN, 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.

Address: https://oj.leetcode.com/problems/gray-code/

Algorithm: assuming that we have completed the first I-bit gray code, we should construct the first I + 1-bit gray according to the following structure: first, the I + 1-bit zero part, the subsequent I-bit is the same as the previous I-bit gray code, followed by the part where I + 1 is 1, the second I-bit is sorted in the reverse order of the first I-bit gray code. If the n = 2gray code is 00 01 11 10, then the Gray Code of N = 3 is 000 001 011 010 110 111 101 100. Code:

 1 class Solution { 2 public: 3     vector<int> grayCode(int n) { 4         vector<int> result; 5         if(n < 0)   return result; 6         result.push_back(0); 7         if(n == 0)  return result; 8         result.push_back(1); 9         for(int i = 1; i < n; ++i){10             int len = result.size();11             int temp = 1 << i;12             for(int j = len-1; j >= 0; --j){13                 result.push_back(result[j] + temp);14             }15         }16         return result;17     }18 };

 

Leetcode: Gray Code