数据结构与算法分析Java版练习1.15

package ch01;

import java.util.Comparator;

/**
 * 练习1.15 定义一个Rectangle类，该类提供getLength和getWidth方法。利用图1-18中的findMax例程编写
 * 			一种main方法，该方法创建一个Rectangle数组并首先找出依面积最大的Rectangle对象，然后
 * 			找出依周长最大的Rectangle对象。
 */
class Rectangle {
	private int width, height;
	public Rectangle(int width, int height) {
		this.width = width;
		this.height = height;
	}
	public int getLength() { return (width + height) << 2; }
	public int getArea() { return width * height; }
	@Override
	public String toString() {
		return "width:" + width + ", height:" + height;
	}
}

public class EX15 {
	public static <T>
	T findMax(T[] a, Comparator<? super T> cmp) {
		int maxIndex = 0;
		for (int i = 0; i < a.length; ++i) {
			if (cmp.compare(a[i], a[maxIndex]) > 0) {
				maxIndex = i;
			}
		}
		return a[maxIndex];
	}
	
	static class LengthComparator implements Comparator<Rectangle> {
		@Override
		public int compare(Rectangle o1, Rectangle o2) {
			// TODO Auto-generated method stub
			if (o1.getLength() == o2.getLength()) return 0;
			else if (o1.getLength() > o2.getLength()) return 1;
			else return -1;
		}		
	}
	
	static class AreaComparator implements Comparator<Rectangle> {
		@Override
		public int compare(Rectangle o1, Rectangle o2) {
			// TODO Auto-generated method stub
			if (o1.getArea() == o2.getArea()) return 0;
			else if (o1.getArea() > o2.getArea()) return 1;
			else return -1;
		}		
	}
	
	public static void main(String[] args) {
		Rectangle[] a = new Rectangle[] {
				new Rectangle(1, 2), new Rectangle(2, 3), new Rectangle(3, 4),
				new Rectangle(2, 9), new Rectangle(2, 5), new Rectangle(5, 5),
		};
		System.out.println(findMax(a, new LengthComparator()));
		System.out.println(findMax(a, new AreaComparator()));
	}
}