Random 3 of 6

anyone have code snippet randomly selecting 3 out of 6 elements, no more, no less?  instance, have 6 led's , want turn 3 of them on... different 3 each time through loop.

this sketch bingo generator, should relative easy transform 3 out of 6.
instead of 90 elements have 6, , instead f drawing 90 draw 3.

code: [select]

//
//    file: bingosequence.ino
//  author: rob tillaart
// version: 0.1.00
// purpose: generate random sequence (optimized)
//    date: 2015-11-01
//     url:
//
// released public domain
//

// seed missing

int bingo[90];

void setup()
{
  serial.begin(115200);
  serial.print("start ");
  serial.println(__file__);

  // fill array values
  (int = 0; < 90; i++)
  {
    bingo[i] = i;
  }
  // swap array values
  (int r = 0; r < 1000; r++)
  {
    int = random(90);
    int j = random(90);
    if (i != j)// swap
    {
      int t = bingo[i];
      bingo[i] = bingo[j];
      bingo[j] = t;
    }
  }

  // print 90 bingo numbers
  (int = 0; < 90; ++i)
  {
    if (i % 10 == 0) serial.println();
    serial.print(bingo[i]);
    serial.print("\t");
  }
  serial.println("\n\nbingo!!!");
}

void loop()
{
}

your turn,

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