cpp_for_professor/Rail_Fencer.cpp at master · JungMYEONG-jin/cpp_for_professor · GitHub

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#include <string>
using namespace std;
std::string encode_rail_fence_cipher(const std::string &str, int n) {

  if(str.empty())
    return str;

  char test[n][str.size()];

  for(int i=0;i<n;i++)
  {
    for(int j=0, len = str.size();j<len;j++)
      test[i][j]='\n';
  }

  // after init

  bool direc = false;
  string res;
  int row=0;
  int col=0;

    for(int j=0, len=str.size();j<len;j++)
    {

      if(row==0 || row==n-1)
        direc=!direc;

      test[row][col++] = str[j];

      direc?row++:row--;


    }


   for(int i=0;i<n;i++)
  {
    for(int j=0, len=str.size();j<len;j++)
    {

      if(test[i][j]!='\n')
        res.push_back(test[i][j]);

      }

     }


  return res;
}

std::string decode_rail_fence_cipher(const std::string &str, int n) {


  if(str.empty())
    return str;

  int len = str.size();

  char test[n][len];

  bool visit[n][len];

  for(int i=0;i<n;i++)
  {
    for(int j=0;j<len;j++)
      test[i][j]='\n';
  }
   for(int i=0;i<n;i++)
  {
    for(int j=0;j<len;j++)
      visit[i][j]=false;
  }

  int row = 0, col=0;
  bool direc=false;


  for(int j=0;j<len;j++)
  {
    if(row==0)
      direc = true;

    if(row==n-1)
      direc =false;


    //test[row][col++]='*'; // mark pos
    visit[row][col++]=true;

    direc?row++:row--;
  }


  int idx=0;
  string res;
  for(int i=0;i<n;i++)
  {
    for(int j=0;j<len;j++)
    {

      if(visit[i][j]==true && idx<len)
        test[i][j]=str[idx++];


    }
  }

  row=0, col=0;
  direc = false;
  for(int i=0;i<len;i++)
  {
    if(row==0)
      direc=true;
    if(row==n-1)
      direc=false;


    res.push_back(test[row][col++]);

    direc?row++:row--;
    cout<<res<<endl;
  }

  return res;
}