Test input: items = [5,5,5,5,4,5,5,5] partition(items, 0, 7) returns 4 and modifies list to [5, 5, 5, 5, 4, 5, 5, 5]. q = 4, which fails A[p...q-1] <= q <= A[q+1 ... r]
Test input: items = [5,5,5,5,4,5,5,5]
partition(items, 0, 7) returns 4 and modifies list to [5, 5, 5, 5, 4, 5, 5, 5].
q = 4, which fails A[p...q-1] <= q <= A[q+1 ... r]