Hu Bugui's model comes from a tragic story: once upon a time, a teenager went out to study. One day, he was unfortunately told that his old father was critically ill, so he hurried home at once. The place where he started was a piece of sand between his home and his home. According to the principle of "the shortest straight line between two points", he took a "shortcut" without hesitation. When he got home, he still didn't see the old man for the last time. The boy regretted it and burst into tears.
Teenagers later heard from their neighbors that when the old man was dying, he kept chanting "Hu Bugui, Hu Bugui means why haven't you come back?" Later, the teenager seriously recalled the road he had traveled. If he doesn't take the sand, he chooses to take the postal route first. Can he go home in time? As a result, this tragic story was later interpreted as a mathematical question.