I’m trying to write a code which tells me the number of inverted pairs

in an array of numbers so that an array like [4,9,6,3,7] will have 9,6

as one inversion, 6,3 as another inversion, but 4,9 won’t be inverted

cos when counting from 1 to infinity, 4 comes before 9… my code gives

me the error of "6:in ‘>’: Comparison of Fixnum with nil failed

(ArgumentError) and here’s the code

1 array=[8,4,2,5,6,9,7,1,3,10]

2 startnum=0

3 nextnum=1

4 count=0

5 while array[startnum] != array[8]

6 if array[startnum] > array[nextnum]

7 count=count+1

8 nextnum=nextnum+1

9 if array[nextnum] == array[9]

10 startnum=startnum+1

11 nextnum=startnum+1

12 end

13 else

14 nextnum=nextnum+1

15 if array[nextnum] == array[9]

16 startnum=startnum+1

17 end

18 end

19 end

20

21 puts count

how do I fix this?