Java语言实现二叉堆的打印代码分享

public class MaxHeap<T extends Comparable<? super T>> {
  private T[] data;
  private int size;
  private int capacity;
 
  public MaxHeap(int capacity) {
    this.capacity = capacity;
    this.size = 0;
    this.data = (T[]) new Comparable[capacity + 1];
  }
 
  public MaxHeap(T[] arr) {//heapify,数组建堆
    capacity = arr.length;
    data = (T[]) new Comparable[capacity + 1];
    System.arraycopy(arr, 0, data, 1, arr.length);
    size = arr.length;
    for (int i = size / 2; i >= 1; i--) {
      shiftDown(i);
    }
  }
 
  public int size() {
    return this.size;
  }
 
  public int getCapacity() {
    return this.capacity;
  }
 
  public boolean isEmpty() {
    return size == 0;
  }
 
  public T seekMax() {
    return data[1];
  }
 
  public void swap(int i, int j) {
    if (i != j) {
      T temp = data[i];
      data[i] = data[j];
      data[j] = temp;
    }
  }
 
  public void insert(T item) {
    size++;
    data[size] = item;
    shiftUp(size);
  }
 
  public T popMax() {
    swap(1, size--);
    shiftDown(1);
    return data[size + 1];
  }
 
  public void shiftUp(int child) {
    while (child > 1 && data[child].compareTo(data[child / 2]) > 0) {
      swap(child, child / 2);
      child /= 2;
    }
  }
 
  /**
   * @param a data数组中某个元素的下角标
   * @param b data数组中某个元素的下角标
   * @return 哪个元素大就返回哪个的下角标
   */
  private int max(int a, int b) {
    if (data[a].compareTo(data[b]) < 0) {//如果data[b]大
      return b;//返回b
    } else {//如果data[a]大
      return a;//返回a
    }
  }
 
  /**
   * @param a data数组中某个元素的下角标
   * @param b data数组中某个元素的下角标
   * @param c data数组中某个元素的下角标
   * @return 哪个元素大就返回哪个的下角标
   */
  private int max(int a, int b, int c) {
    int biggest = max(a, b);
    biggest = max(biggest, c);
    return biggest;
  }
 
  public void shiftDown(int father) {
    while (true) {
      int lchild = father * 2;
      int rchild = father * 2 + 1;
      int newFather = father;//这里赋不赋值无所谓，如果把下面这个return改成break,那就必须赋值了
 
      if (lchild > size) {//如果没有左、右孩子
        return;
      } else if (rchild > size) {//如果没有右孩子
        newFather = max(father, lchild);
      } else {//如果有左、右孩子
        newFather = max(father, lchild, rchild);
      }
 
      if (newFather == father) {//如果原父结点就是三者最大，则不用继续整理堆了
        return;
      } else {//父节点不是最大，则把大的孩子交换上来，然后继续往下堆调整，直到满足大根堆为止
        swap(newFather, father);
        father = newFather;//相当于继续shiftDown(newFather)。假如newFather原来是father的左孩子，那就相当于shiftDown(2*father)
      }
    }
  }
 
  public static <T extends Comparable<? super T>> void sort(T[] arr) {
    int len = arr.length;
    MaxHeap<T> maxHeap = new MaxHeap<>(arr);
    maxHeap.printAsTree();
    for (int i = len - 1; i >= 0; i--) {
      arr[i] = maxHeap.popMax();
    }
  }
 
  public static void printArr(Object[] arr) {
    for (Object o : arr) {
      System.out.print(o);
      System.out.print("\t");
    }
    System.out.println();
  }
 
  public void printSpace(int n) {//打印n个空格(在这里用‘\t'来代替)
    for (int i = 0; i < n; i++) {
      System.out.printf("%3s", "");
    }
  }
 
  public void printAsTree() {
    int lineNum = 1;//首先遍历第一行
    int lines = (int) (Math.log(size) / Math.log(2)) + 1;//lines是堆的层数
    int spaceNum = (int) (Math.pow(2, lines) - 1);
    for (int i = 1; i <= size; ) { //因为在[1...size]左闭右闭区间存数据，data[0]不存数据
       
      //每层都是打印这个区间[2^(层数-1) ... (2^层数)-1]。如果堆里的数不够(2^层数)-1个，那就打印到size。所以取min((2^层数)-1,size).
      for (int j = (int) Math.pow(2, lineNum - 1); j <= Math.min(size, (int) Math.pow(2, lineNum) - 1); j++) {
        printSpace(spaceNum); //打印spaceNum个空格
        System.out.printf("%3s", data[j]);//打印数据
        System.out.printf("%3s", "");//图片中绿色方框
        printSpace(spaceNum);//打印spaceNum个空格
        i++;//每打印一个元素就 + 1
      }
      lineNum++;
      spaceNum = spaceNum / 2;
      System.out.println();
    }
  }
 
  public static void main(String args[]) {
    Integer[] arr = {3, 5, 1, 7, 2, 9, 8, 0, 4, 6, 1, 3, 6, 1, 1};
    sort(arr);
  }
}