package net.obsearch;
   
   import java.util.logging.Logger;
   
   import org.junit.Test;
   public class TestQs {
   	static Logger logger = Logger.getLogger(TestQs.class.getSimpleName());
   	
   	
  	public static void combiCounter(char[] chars){
  		long counter = 1;
  		long end = (long)Math.pow(2, chars.length);
  		while(counter <= end){
  			printChars(counter, chars);
  			counter++;
  		}
  	}
  	
  	public static void printChars(long counter, char[]chars){
  		int i = 0;
  		while(i < chars.length){
  			if((counter & (1 << i)) != 0){
  				System.out.print(chars[i]);
  			}
  			i++;
  		}
  		System.out.println();
  	}
  	
  	public static void combiRecursive(char[] chars){
  		 combiRecursiveAux(chars, 0, new StringBuilder(), new boolean[chars.length]);
  	}
  	
  	
  	public static void combiRecursiveAux(char[] chars, int start, StringBuilder buf, boolean[] flags){
  		int i = start;
  		while(i < chars.length){
  			if(flags[i]){
  				i++;
  				continue;
  			}
  			buf.append(chars[i]);
  			System.out.println(buf.toString());
  			flags[i] = true;			
  			combiRecursiveAux(chars, start, buf, flags);
  			flags[i] = false;
  			buf.setLength(buf.length() - 1);				
  			i++;
  		}
  	}
  	
  	@Test
  	public void testCombi(){
  		//combiCounter(new char []{'w', 'x', 'y', 'z'});
  		combiRecursive(new char []{'w', 'x', 'y', 'z'});
  	}
  	
  }