打印二叉堆(Java实现)

java

打印二叉堆:利用层级关系

我这里是先将堆排序,然后在sort里执行了打印堆的方法printAsTree()

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);

}

}

  执行结果:

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