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  1. /* package whatever; // don't place package name! */
  2.  
  3. import java.util.*;
  4. import java.lang.*;
  5. import java.io.*;
  6.  
  7. /* Name of the class has to be "Main" only if the class is public. */
  8. class Ideone
  9. {
  10. 	public static void main (String[] args) throws java.lang.Exception
  11. 	{
  12. 	    List<List<String>> combList = new ArrayList<>();
  13. 	    combList.add(Arrays.asList("a1", "a2", "a3"));
  14. 	    combList.add(Arrays.asList("b1", "b2"));
  15. 	    combList.add(Arrays.asList());
  16. 	    combList.add(Arrays.asList("c1", "c2", "c3"));
  17.  
  18. 	    combinations(combList, 0, 0, "");
  19. 	}
  20.  
  21. 	public static void combinations(List<List<String>> combList, int listIndex, int itemIndex, String result)
  22. 	{
  23. 	    // Am I at the bottom of the y-axis?
  24. 	    if(listIndex < combList.size())
  25. 	    {
  26. 	        //Am I at the bottom of the x-axis?
  27. 	        if(itemIndex < combList.get(listIndex).size())
  28. 	        {
  29. 	            List<String> curList = combList.get(listIndex);
  30. 	            StringBuilder sb = new StringBuilder();
  31. 	            sb.append(result).append(curList.get(itemIndex)).append(" ");
  32. 	            combinations(combList, listIndex + 1, 0, sb.toString());
  33. 	            combinations(combList, listIndex, itemIndex + 1, result);
  34. 	        }else if (combList.get(listIndex).isEmpty()){
  35. 	            combinations(combList, listIndex + 1, 0, result);
  36. 	        }
  37. 	        return;
  38. 	    }
  39. 	    System.out.println(result);
  40. 	    //return; - redundant as last instruction of method
  41. 	}
  42. }
Success #stdin #stdout 0.04s 2184192KB
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Standard input is empty
stdout
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a1 b1 c1 
a1 b1 c2 
a1 b1 c3 
a1 b2 c1 
a1 b2 c2 
a1 b2 c3 
a2 b1 c1 
a2 b1 c2 
a2 b1 c3 
a2 b2 c1 
a2 b2 c2 
a2 b2 c3 
a3 b1 c1 
a3 b1 c2 
a3 b1 c3 
a3 b2 c1 
a3 b2 c2 
a3 b2 c3
https://ideone.com/wpIaNe
language:
Java (HotSpot 12)
created:
6 years ago
visibility:
public

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