trees and external storage merge into arr (arr is now empty read - into arr merge into arr write to disk merge into arr (arr is now empty read - into arr merge into arr write to disk merge into arr write to disk this last sequence of steps is rather lengthyso it may be helpful to examine the details of the array contents as the steps are completed figure shows how these arrays look at various stages of mergesort adarr arr arr arr arr to disk arr steps and earr arr arr arr arr step to disk steps and cfarr arr arr arr arr to disk arr steps and figure step barr array contents during mergesort step to disk