Andy: AC code for UVa#12455 but without comment.
Merge branch 'master' of github.com:Judge-Team/UVa-Online-Judge
Fix warning
Andy: Update comment.
Merge branch 'master' of github.com:Judge-Team/UVa-Online-Judge
Andy: Fix the issue of loop within one city.
Implement czchen-12455
Merge branch 'czchen/12455'

* czchen/12455:
  Implement czchen-12455