leetcode_89 title--gray Code (Backtracking method)

Gray CodeTotal accepted:32175 Total submissions:98703my submissions QuestionSolution

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:

00-001-111-310-2

Note:
For a given n, a gray code sequence is not uniquely defined.

For example, was [0,2,3,1] 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.

Hide TagsBacktrackingThe problem is to give the N value, give the N-bit gray code corresponding to the number of the vector, this problem uses backtracking, because n bits and n-1 bit of gray code is related, the first half of the same as the n-1 bit. The latter part is 2^n-1 by the front part of the symmetry, so recursion is used to retrace the return. The following is the AC code

#include <iostream> #include <vector> #include <queue>using namespace std;int conversion (int n) {int Temp=1;if (n==1) return 1;for (int i=1;i<n;i++) Temp=temp*2;return temp;} vector<int> Graycode (int n) {vector<int> result;if (n==0) {result.push_back (0); return result;} if (n==1) {result.push_back (0); Result.push_back (1); return result;} Else{//queue<int> Temp;result=graycode (n-1); int len=result.size (); for (int i=len-1;i>=0;--i) {int temp= Result[i]+conversion (n); result.push_back (temp);} return result;}} int main () {vector<int> Temp=graycode (4); for (int i=0;i<temp.size (); i++) Cout<<temp[i]<<endl;}

　　

leetcode_89 title--gray Code (Backtracking method)