how to find total number of numbers whose binary representation is palindrome?

Question

What is the best approach to find the total number of numbers between two given numbers whose binary representation is palindrome? The problem I am trying to solve is here on spoj http://www.spoj.com/problems/BINPALI/

Answer 1

I solved the spoj problem and code as below:

#include<iostream>
#include<algorithm>
#include<cctype>
#include<cstring>
#include<string>
using namespace std;
int main()
{
  int a,b,t;
  cin>>t;
  while(t--)
  {
     cin>>a>>b;
     int total=0;
     string s="";
     while(a<=b)
     {
       s="";
       for(int i=a;i>0;i=i/2)
       {
         if(i%2)
            s+='1';
         else
            s+='0';
       }
      string s2="",s3="";
      s2=s.substr(0,s.length()/2);
      int k=s.length();
      if(k%2)
        s3=s.substr(s.length()/2+1,s.length());
      else
        s3=s.substr(s.length()/2,s.length());
      reverse(s2.begin(),s2.end());
      if(s2==s3)
      {
         cout<<a<<" ";
         total++;
      }
      a++;
   }
if(!total)
    cout<<"none"<<endl;
}
return 0;
}