Leetcode 89. Gray Code

文章作者：Tyan
博客：noahsnail.com  |  CSDN  |  简书

1. Description

2. Solution

• Version 1

class Solution {
public:
    vector<int> grayCode(int n) {
        vector<int> result;
        bitset<32> code;
        traverse(result, code, n - 1);
        return result;
    }

private:
    void traverse(vector<int>& result, bitset<32>& code, int pos) {
        if(pos < 0) {
            int value = code.to_ulong();
            result.push_back(value);
            return;
        }
        traverse(result, code, pos - 1);
        code.flip(pos);
        traverse(result, code, pos - 1);
    }
};

• Version 2

class Solution {
public:
    vector<int> grayCode(int n) {
        vector<int> result;
        int code = 0;
        traverse(result, code, n - 1);
        return result;
    }

private:
    void traverse(vector<int>& result, int& code, int pos) {
        if(pos < 0) {
            result.push_back(code);
            return;
        }
        traverse(result, code, pos - 1);
        code ^= (1 << pos);
        traverse(result, code, pos - 1);
    }
};

Reference

1. https://leetcode.com/problems/gray-code/description/