Simulator

说明：  模拟蚂蚁和食蚁兽的生存规律。在20X20的网格世界里，每个生物每次可向四个方向移动（但不会移除网格边缘），食蚁兽会吃掉在他目标处的蚂蚁(The goal for this programming project is to create a simple 2D predator-prey simulation. In this simulation the prey are ants and the predators are doodlebugs. These critters live in a world composed of a 20x20 grid of cells. Only one critter may occupy a cell at a time. The grid is enclosed, so a critter is not allowed to move off the edges of the world. Time is simulated in time steps. Each critter performs some action every time step.)