我正在尝试从此网址中删除表格： ＆＃34; https://hutdb.net/17/players＆＃34; 我花了很多时间学习rvest并使用了selectorgadget，但每当我尝试获取输出时，我总会得到相同的错误（Character（0））。
import java.util.ArrayList;
import java.util.Iterator;
import java.util.List;
public class AvlTree {
private Node root;
private int size;
/**
* default constructor.
*/
public AvlTree() {
this.root = null;
this.size = 0;
}
/**
* A constructor that builds a new AVL tree containing all unique values in the input
* array
*
* @param data the values to add to tree
*/
public AvlTree(int[] data) {
for (int i = 0; i < data.length; i++) {
add(data[i]);
}
}
/**
* A copy constructor that creates a deep copy of the given oop.ex4.data_structures.AvlTree. The new tree
* contains all the values of the given tree, but not necessarily in the same structure.
*
* @param avlTree an AVL tree.
*/
public AvlTree(AvlTree avlTree) {
}
/**
* Add a new node with the given key to the tree.
*
* @param newValue the value of the new node to add.
* @return true if the value to add is not already in the tree and it was successfully added,
* false otherwise.
*/
public boolean add(int newValue) {
if (root == null) {
root = new Node(newValue);
size++;
return true;
}
Node current = root;
Node parent = null;
while (current != null) {
if (current.getData() == newValue) {
return false;
}
parent = current;
if (newValue < current.getData()) {
current = current.getChildernLeft();
} else {
current = current.getChildernRight();
}
}
size++;
// when we here the new NODE Need to be chiled of Node hashmor in parent.
// addHelper is adding the new Node.2
// addHelper(newNodeToAdd, current);
return true;
}
private void addHelper(Node newNodeToAdd, Node current) {
// if (newNodeToAdd.getData() > current.getData()) {
// if (current.getChildernRight() == null) {
// current.setChildernRight(newNodeToAdd);
// } else {
// addHelper(newNodeToAdd, current.getChildernRight());
// }
// } else {
// if (current.getChildernLeft() == null) {
// current.setChildernLeft(newNodeToAdd);
// } else {
// addHelper(newNodeToAdd, current.getChildernLeft());
// }
// }
}
/**
* Check whether the tree contains the given input value.
*
* @param searchVal the value to search for.
* @return the depth of the node (0 for the root) with the given value if it was found in the tree, −1 otherwise.
*/
public int contains(int searchVal) {
Node current = root;
int depth = 0;
while (current != null) {
if (current.getData() == searchVal) {
return depth;
}
depth++;
if (searchVal < current.getData()) {
current = current.getChildernLeft();
} else {
current = current.getChildernRight();
}
}
return -1;
}
/**
* Removes the node with the given value from the tree, if it exists.
*
* @param toDelete the value to remove from the tree.
* @return true if the given value was found and deleted, false otherwise.
*/
public boolean delete(int toDelete) {
size -= 1;
return true;
}
/**
* @return the number of nodes in the tree.
*/
public int size() {
return size;
}
/**
* @return an iterator for the Avl Tree. The returned iterator iterates over the tree nodes.
* in an ascending order, and does NOT implement the remove() method.
*/
public Iterator<Integer> iterator(){
List myList=new ArrayList<>();
Node counter=root;
Node counter1=root.getChildernLeft();
if(counter1==null){
myList.add(counter1);
}
Node counter1=root.getChildernLeft();
}
/**
* Calculates the minimum number of nodes in an AVL tree of height h
*
* @param h the height of the tree (a non−negative number) in question.
* @return the minimum number of nodes in an AVL tree of the given height.
*/
public static int findMinNodes(int h) {
// I SOVLE THIS WITH ROCKISA
int counterMin = 0;
if (h == 0) {
return counterMin = 1;
}
if (h == 1) {
return counterMin = 2;
}
return (findMinNodes(h - 1) + findMinNodes(h - 2) + 1);
}
/**
* Calculates the maximum number of nodes in an AVL tree of height h.
*
* @param h the height of the tree (a non−negative number) in question.
* @return the maximum number of nodes in an AVL tree of the given height.
*/
public static int findMaxNodes(int h) {
int counterMax = 0;
for (int i = 0; i < h; i++) {
counterMax += Math.pow(h, i);
}
return counterMax;
}
/**
* @return
*/
public String toString() {
if (root == null) {
return "";
}
return root.toString();
}
//THIS IS OK
public void RotationRr(Node valRotation) {
if (valRotation == root) {
Node keepRootChild = root.getChildernRight();
root.setChildernRight(null);
}
Node parent1 = valRotation.getParent();
Node keepRightChild = valRotation.getChildernRight();///4
valRotation.setChildernRight(null);
keepRightChild.setParent(parent1);
if (!keepRightChild.hasChildrenLeft()) {
keepRightChild.setChildernLeft(valRotation);
valRotation.setParent(keepRightChild);
} else {
keepRightChild.getChildernLeft().addNode(valRotation);
}
}
public void RotationLr(Node valRotation) {
RotationLl(valRotation);
}
/**
* ........CHECK.....!!!!TODO
*
* @param valRotation
*/
public void RotationLl(Node valRotation) {
Node parent2 = valRotation.getParent();
Node keepLeftChild = valRotation.getChildernLeft();
valRotation.setChildernLeft(null);
keepLeftChild.setParent(parent2);
if (!keepLeftChild.hasChildrenRight()) {
keepLeftChild.setParent(keepLeftChild);
} else {
keepLeftChild.getChildernRight().addNode(valRotation);
}
}
public void RotationRl(Node valRotation) {
RotationRr(valRotation);
}
public static void main(String[] args) {
AvlTree avlTree = new AvlTree();
avlTree.add(7);
avlTree.add(2);
System.out.println(avlTree.contains(2));
// System.out.println(avlTree.contains(5));
avlTree = new AvlTree();
avlTree.add(2);
avlTree.add(7);
System.out.println(avlTree.contains(2));
// System.out.println(avlTree);
}
}
任何帮助都将不胜感激。
答案 0 :(得分：0)
数据是动态加载的，无法直接从html中检索。但是，例如，在Chrome DevTools中查看“网络”，我们可以在https://hutdb.net/ajax/stats.php?year=17&page=0&selected=OVR&sort=DESC找到格式正确的JSON
library(jsonlite)
dat <- fromJSON("https://hutdb.net/ajax/stats.php?year=17&page=0&selected=OVR&sort=DESC")
输出如下：
# results aOVR id League Year Card Team Player Position Type Shoots HGT
# 1 6308 6308 <NA> <NA> <NA> <NA> <NA> <NA> <NA> <NA> <NA> <NA>
# 2 <NA> 2030 11782 NHL 17 MOV OTT Erik Karlsson RD OFD Right 6'0
# 3 <NA> 2060 11785 NHL 17 MOV TBL Victor Hedman LD TWD Left 6'6
# 4 <NA> 2008 11791 NHL 17 MOV CHI Patrick Kane RW SNP Left 5'11
# 5 <NA> 2058 13845 NHL 17 SCE ANA Ryan Getzlaf C PWF Right 6'4
# 6 <NA> 2074 11824 NHL 17 MOV BOS Brad Marchand LW TWF Left 5'9
# 7 <NA> 2008 11829 NHL 17 MOV EDM Connor McDavid C PLY Left 6'2
# 8 <NA> 2048 11840 NHL 17 MOV WSH Nicklas Backstrom C PLY Left 6'1
# 9 <NA> 2058 11841 NHL 17 MOV PIT Sidney Crosby C PLY Left 5'11
# 10 <NA> 2065 13644 NHL 17 TOTY WPG Patrik Laine RW TWF Right 6'3
# 11 <NA> 2008 13645 NHL 17 TOTY EDM Connor McDavid C PLY Left 6'2
# 12 <NA> 2039 13680 NHL 17 TOTY LAK Drew Doughty RD TWD Right 6'1
# 13 <NA> 2063 13689 NHL 17 TOTY BOS Patrice Bergeron C TWF Right 6'2