"One Day together Leetcode" #89. Gray Code

One Day together Leetcode

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(i) Title

The gray code is a binary numeral system where the successive values are 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] was also a valid gray code sequence according to the above definition.

For now, the judge are able to judge based on one instance of gray code sequence. Sorry about that.

(ii) Problem solving

Topic: Given an integer n, generates an n-bit gray code.

Before the problem of gray code, each time in the n-1 bit gray code behind plus 0 and 1 composed of n-bit gray code.

The title refers only to the sequence of gray codes given in the example.

Therefore, it is easy to find the law, each time from the n-1 bit gray code tail forward, followed by a 2 of the n-1 to get the new n-bit gray code.

The code is as follows:

classSolution { Public: vector<int>Graycode (intN) { vector<int>Retif(n==0) {//For 0, special handling is requiredRet.push_back (0);returnRet } for(inti =0; I < n; i++) {if(i==0)//Here represents 1-bit gray code{Ret.push_back (0); Ret.push_back (1); }Else{ for(intj = ret.size ()-1; J >=0; j--)//each time from the tail of the n-1-bit gray code to forward, once plus 2 of the n-1 to get the new gray code{Ret.push_back (POW(2, i) +ret[j]); }            }        }returnRet }};

"One Day together Leetcode" #89. Gray Code