using ``heapq`` in ``main_cli``
(cherry picked from commit f6453bbd3496c24455ce7dada91bc2f6b136d7e4)
using ``heapq`` in GUI
(cherry picked from commit 313dc7754a8c336e8131904549bad0913e99c3d5)
replaced float ``1.0`` to str ``'1.0'`` for tkinter
(cherry picked from commit 028a3cc080e3a6ef312d4a5b4a10b592915d7d23)