xxxxxxxxxx
[2, 1, 2, 2, 6, 5, 0, 2, 0, 5, 5, 7, 7, 4, 3, 3, 9] -->
2+2+6 0+2+0 5+5+7+7 3+3+9
[2, 1, 10, 5, 2, 24, 4, 15 ] -->
2+24+4
[2, 1, 10, 5, 30, 15 ]
The length of final array is 6