string palindrome(string str)
{
 
	int n=sz(str);
 
	for(int l=n-1;l>=0;l--)//Palindrome can be of any size.
	{
		for(int i=0;i<n-l+1;i++)
		{
			int j=i+l-1;
 
			string str2=str.substr(i,j-i+1);
 
			if(check_pal(str2)) return str2;//check_pal simply checks whether //the string is palindrome or not.
		}
	}
 
	string t1="";
	return t1;
}

#define MAX 128
bool check(const char *str, const char *ori)
{
   return ((stricmp(str,ori)==0)?true:false);
}
 
std::string palindrome(const char *str)
{
   int size=strlen(str);
   if(size>=MAX)
      return "failed";
   char reverse_str[MAX]={NULL};
   for(int i=0,j=((size)-1);i<size;i++,j--)
      reverse_str[i]=str[j];
   if(check(reverse_str,str))
      return reverse_str;
   return "it's not a palindrome";
}
 
int main()
{
   std::string m_str=palindrome("dlrow olleh hello world");
   std::cout<<m_str;
   std::cin.get();
   return 0;   
}

 
bool check(const std::string str, const std::string ori)
{
   return ((stricmp(str.c_str(),ori.c_str())==0)?true:false);
}
 
std::string palindrome(const std::string str)
{
   int size=str.length();
   std::string reverse_str;
   for(int i=((size)-1);i>=0;i--)
      reverse_str.push_back(str[i]);
   if(check(reverse_str,str))
      return reverse_str;
   return "it's not a palindrome";
}
 
int main()
{
   std::string m_str=palindrome("dlrow olleh hello world");
   std::cout<<m_str.c_str();
   std::cin.get();
   return 0;   
}

// do some convolution
string getLongestPalindrome(string fwd){
   string rev = string(fwd.rbegin(), fwd.rend());
   int sz = fwd.size();
   int maxcount = 0, maxstart = 0;
   int start = 0, end = 0, count = 0;
 
   for(int overlap = 1; overlap <= 2*sz; overlap++){
      count = 0;
   	for(int i = 0; i < overlap; i++){
   	   int index1 = sz - overlap + i;
   		if(index1 >= 0 && index1 < fwd.size() && i < rev.size() && fwd[index1] == rev[i]){
   		   if(!count){
               start = i;
               end = i;
               }
 
            count++;
            }
         else{
            if(count > maxcount){
               maxcount = count;
               maxstart = start;
               }
 
            count = 0;
            }
   		}
   	}
 
   if(count > maxcount){
      maxcount = count;
      maxstart = start;
      }
 
   return rev.substr(maxstart, maxcount);
   }