GrayCode.cpp

#include<bits/stdc++.h>
using namespace std;

// this code return nth gray code
//https://leetcode.com/problems/gray-code/
vector<int>  grayCode (int n)
{
    int lmt = 1 << n;
    cout << lmt << endl;
    vector<int> ans;
    for(int i = 0; i < lmt; i++){
            int x = i;
        ans.push_back(x ^ (x >> 1));
    }
    return ans;
}

int rev_grayCode(int g)
{
    int n = 0;
    for(; g; g >>= 1)
        n ^= g;
    return n;
}


///https://www.geeksforgeeks.org/gray-to-binary-and-binary-to-gray-conversion/
char xor_c(char a, char b) {return (a == b) ? '0' : '1';}
char flip(char c) {return (c == '0') ? '1' : '0' ;}
// convert binary to Gray
string BtoG(string binary)
{
    string gray = "";
    gray += binary[0]; // MSB same

    for(int i = 1; i < binary.size(); i++)
        gray += xor_c(binary[i - 1], binary[i]);

        return gray;
}

string GotB(string gray)
{
    string binary = "";
    binary += gray[0];

    for(int i = 1; i < gray.size(); i++){
        if(gray[i] == '0') binary += binary[i - 1];
        else binary += flip(binary[i - 1]);
    }
    return binary;
}
int main()
{
   /*
   int n;
    cin >> n;
  //  auto v = grayCode(n);
     cout << rev_grayCode(n)<<endl;
//    for(auto x: v)cout << x << " ";
    return 0;
    //*/

   /**
    int T;
    cin >> T;
    while(T--){
        string s;
        cin >> s;
        cout << BtoG(s)<<endl;
    }
    return 0;
    **/
    
    
}