r[3]=0  18 19  . 21 22  .
r[0]=2         0  .  .  3  4  .
r[4]=7                       24  . 26  .  . 29
r[1]=7                        .  7  .  . 10  .
r[2]=12                                      . 13  . 15  .  .
r[5]=13                               30  .  .  . 34  .

keys: 18 19  0 21 22  3  4 24  7 26 30 10 29 13 34 15
index: 0  1  2  3  4  5  6  7  8  9 10 11 12 13 14 15

Figure 4: Result after step 3 of the first-fit decreasing method.