数据结构与算法分析Java版练习1.14

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package ch01;import java.util.Random;/** * 练习1.14 设计一个泛型类OrderedCollection,它存储Comparable的对象的集合（在数组中），以及 * 该集合的当前大小。提供public方法isEmpty、makeEmpty、insert、remove、findMin和 * findMax。findMin和findMax分别返回该集合中最小和最大的Comparable对象的引用，如果 * 该集合为空，则返回null。 * */class OrderedCollection<T extends Comparable<T>> {private final static int DEFAULT_CAPACITY = 10;private Comparable<T>[] items;private int size;public OrderedCollection() {size = 0;ensureCapacity(DEFAULT_CAPACITY);}public boolean isEmpty() {return size == 0;}public void makeEmpty() {if (size == 0) {return;}for (int i = 0; i < size; ++i) {items[i] = null;}size = 0;}public boolean insert(T x) {//insert(size(), x);int index = binarySearch0(0, size() - 1, x);if (index >= 0)insert(index, x);elseinsert(-index - 1, x);return true;}private void insert(int idx, T x) {if (items.length == size())ensureCapacity(size() * 2 + 1);for (int i = size; i > idx; i--)items[i] = items[i - 1];items[idx] = x;size++;}/** * 这个函数是从Arrays.java中摘抄过来的。 */private int binarySearch0(int fromIndex, int toIndex,            T key) {int low = fromIndex;int high = toIndex;while (low <= high) {int mid = (low + high) >>> 1;T midVal = (T)items[mid];if (midVal.compareTo(key) < 0)low = mid + 1;else if (midVal.compareTo(key) > 0)high = mid - 1;elsereturn mid; // key found}return -(low + 1);  // key not found.}private T remove(int idx) {T removedItem = (T)items[idx];for (int i = idx; i < size() - 1; ++i)items[i] = items[i+1];items[size() - 1] = null;size--;return removedItem;}public boolean remove(T x) {int index = 0;boolean found = false;while (index >= 0) {index = binarySearch0(0, size() - 1, x);if (index >= 0) {remove(index);found = true;}}return found;}public boolean isPresent(T x) {int index = binarySearch0(0, size() - 1, x);if (index >= 0)return true;return false;}public T findMin() {if (size() != 0)return (T)items[0];return null;} public T findMax() {if (size() != 0)return (T)items[size() - 1];return null;} private void ensureCapacity(int newCapacity) {if (newCapacity < size)return;Comparable<T>[] old = items;items = (Comparable<T>[])new Comparable[newCapacity];for (int i = 0; i < size(); ++i)items[i] = old[i];}public int size() {return size;}public void display() {for (int i = 0; i < size(); ++i) {System.out.print(items[i] +" ");}//System.out.println();}}public class EX14 {public static void main(String[] args) {OrderedCollection<Integer> intColl = new OrderedCollection<Integer>();Random rand = new Random(47);for (int i = 0; i < 15; ++i) intColl.insert(rand.nextInt(15) + 1);System.out.print("The Ints: "); intColl.display();System.out.println();System.out.println("isEmpty: " + intColl.isEmpty());System.out.println("if removed 6: " + intColl.remove(6));System.out.println("if removed 11: " + intColl.remove(11));System.out.println("if removed 14: " + intColl.remove(14));System.out.print("The Ints: "); intColl.display();System.out.println();System.out.println("find min: " + intColl.findMin());System.out.println("find max: " + intColl.findMax());System.out.print("make it empty:");intColl.makeEmpty();intColl.display();System.out.println();System.out.println("isEmpty: " + intColl.isEmpty());}}
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