简单的数学计算游戏 两个函数 showEquation() checkAnswer(equation, ans)-easy math game

人机对战的俄罗斯方块游戏，AI策略采用数学公式计算每个可以放置方块的位置的得分，路径搜索采用A星搜索，从而实现人机对战-Human battle with AI in this tetris game.AI use mathematical formulas to compute the score of every enable position which can put block .Then I use A* algorithm to search path.