Finish queue assignment.

There are some errors.
Submission result:
Compilation:  PASSED
Style:        FAILED
Findbugs:     No potential bugs found.
API:          PASSED

Correctness:  30/35 tests passed
Memory:       44/49 tests passed
Timing:       18/24 tests passed

Raw score: 83.44% [Correctness: 65%, Memory: 10%, Timing: 25%, Style: 0%]