很多人遇到过这样的游戏題目:你能把圖1上的圆形不重复地一笔画成嗎,公园中的羊腸小徑(圖2),游人能一次不重复地走遍每一条小徑嗎?像这一类的游戏都称为“一笔画”。这一类的游戏往往不是每一个人都能够玩好的。有的时候,費上九牛二虎之力才算画了出来。有的时候,不管你怎样設法,画来画去还是不能画出来。常 Many people have encountered such a game title: Can you draw the circle in Figure 1 without a single stroke? In the park, the gut trail (Figure 2) allows visitors to walk through each trail without repeating it. Like this type of game is called “stroke painting.” This type of game is often not everyone can play well. Sometimes, it took a lot of money to figure it out. Sometimes, no matter how you manage to draw, you can’t draw it or draw it. often