Activation Tree

The flow of control of the call quicksort(1,9) would be like

Execution begins ..

enter readarray

exit readarray

enter quicksort(1,9)

enter partition(1,9)

exit partition(1,9)

enter quicksort(1,3)

exit quicksort(1,3)

enter quicksort(5,9)

exit quicksort(5,9)

exit quicksort(1,9)

Execution terminates

When the information is represented as an activation tree we get the tree as shown.