Question $1)$

Let $A[0..n-1]$ be an array of $n$ real numbers. A pair $($A $[$i$],$ A$[$j$])$ is said to be an inversion if these numbers are out of order, i$.$e$.,A[i]>A[j]i$ but $A[i]>A[j].$ Design the most efficient algorithm for counting the number $of$ inversions. What $is$ the time complexity $of$ your solution?