Codevita 2017 Round-1 Problem-C

Problem:
CodeVita 2017 Round 1 Problem -C
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http://s000.tinyupload.com/?file_id=52952119059621072275

Solution:

/*
 Author: Krishankant Ray
 * CodeVita 2017 Round 1
 */

#include<iostream>
#include<vector>

using namespace std;
int main()
{
    int d,k=0;
    string arr;
    cin>>d;
    cin>>arr;
    int n=arr.length();
    char R[n];

    for(int f=0; f<n; )
    {

        R[f]=arr[k++];

        f+=((2*d)-2);
    }
    for(int i=1; i<d-1;i++)
    {
        R[i]=arr[k++];
        for(int j=i; j<n;)
        {

            j+=((2*d)-2-(2*i));
            R[j]=arr[k++];

            j+=((2*i));
            if(j<n)
            R[j]=arr[k++];

        }
    }

    for(int l=d-1; l<n;l+=((2*d)-2))
    {
        R[l]=arr[k++];

    }
    for(int f=0; f<n;f++)
    {
        if(R[f]=='X')
            break;
        else
        cout<<R[f];
    }

    return 0;
}