【原】Java自测题编写代码：CS455 Random Walk

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In this assignment you will write a graphics-based program to do a random walk, sometimes also known as a drunkard’s walk.

This random walk simulates the wandering of an intoxicated person on a square street grid. The drunkard will start out in the middle of the grid and will randomly pick one of the four compass directions, and take a step in that direction, then another step from that new location in a random direction, etc.

This assignment will give you practice with creating classes, using loops, using the java library for random number generation, doing console-based IO, and drawing to a graphics window. Also you’ll get practice in general program development.

Analysis

Randow Walk，即随机游走问题，类似布朗运动，物体在下一刻走动的方向完全是随机的。本题利用随机数生成器来模拟下一刻的方位。框架使用java的awt包实现了UI部分，我们只需要将随机算法加入到提供的框架中。
解题的关键是了解随机数生成器的用法，根据提供的框架，找到对应函数入口，根据给定的测试集进行调试即可。

Tips

从测试函数入口入手

private void testTranslate(Impoint loc, int deltaX, int deltaY) {
  ...
  ImPoint p2 = loc.translate(deltaX, deltaY);
  ...
}

因此我们需要实现ImPoint类，以及translate方法，核心代码如下

class ImPoint {
  private int x;
  private int y;
  ...
  public Impoint translate(int deltaX, int deltaY) {
    Random r = new Random();
    int x = deltaX + nextInt(2) - 1;
    int y = deltaY + nextInt(2) - 1;
    return new Impoint(x, y);
  }
  ...
}

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