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  • Gray Code -- LeetCode

    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.

    思路:利用位运算,将当前结果中的所有数最前面添上一个1,直到达到n位位置。时间复杂度O(n)

     1 class Solution {
     2 public:
     3     vector<int> grayCode(int n) {
     4         vector<int> res(1, 0);
     5         if (n == 0) return res;
     6         int offset = 1;
     7         for (int i = 0; i < n; i++)
     8         {
     9             for (int j = res.size() - 1; j >= 0; j--)
    10                 res.push_back(res[j] | offset);
    11             offset = offset << 1;
    12         }
    13         return res;
    14     }
    15 };
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  • 原文地址:https://www.cnblogs.com/fenshen371/p/5168208.html
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