MPGH Decrypter [Challenge]

#include <iostream>

using namespace std;

void toBinary(int n,char* str,int d){
	if(d<0)return;	
	str[d-1]=n%2+'0';	
	toBinary(n>>1,str,d-1);	
}

int toDecimal(char* str,int d){
	if(d<=1)return str[0]-'0';
	return ((str[0]-'0')<<(d-1))+toDecimal(str+1,d-1);
}

char* encrypt(char* str){

	int i,j;
	int len = (strlen(str))*8;
	char* str2=new char[len+1];
	
	
	for(i=0;i<(strlen(str))*8;i++){
		str2[i]='0';
	}
	
	for(i=0;i<strlen(str);i++){
		int n = (int)str[i];
		toBinary(n,str2+i*8,8);
	}

	str2[len]='\0';
	char tstr[5];
	memcpy(tstr,str2,4);
	tstr[4]='\0';
	
	strcpy(str2,str2+4);
	strcpy(str2+len-4,tstr);


	char* encryptedStr=new char[len/4+1];
	
	char map[]="0123456789ABCDEF";
	for(i=0;i<len/4;i++){
		encryptedStr[i]=map[toDecimal(str2+4*i,4)];
	}
	encryptedStr[i]='\0';

	
	return encryptedStr;

}


int main(void){

char str[256];
gets(str);
char* encrypterStr = encrypt(str);
cout<<encrypterStr;


}

void toBinary(int n, char* str, int d) {
  if (d == 0)
    return;
    
  str[d - 1] = n % 2 + '0';
  toBinary(n >> 1, str, d - 1); 
}