In general, your solution fails whenever there are multiple highest elements where element-bs-1==0 inside the priority queue. while that particular top element is finished, the other top elements are not and still have a value of 1. (eg. multiple 2s, bs=1) Here's a counterexample demonstrating this:

10

1 1 1 1 2 2 2 2 2

(Answer should be 5)

If you remove the line that handles this, your solution should work.