我应该在优先级的最小排队中返回最古老的元素以及所述元素。我必须使用节点,阵列是可选的。这是我到目前为止得到的,但是我在第20行上有一个无效的指针错误,我不知道如何修复它。请帮助
public class MinHeap {
public static int timeStamp = 0;
public static int ts = 0;
public static int maxTime = 0;
public static Node root;
public MinHeap(){
this.root = null;
}
public static void insert(int id, int ts){
timeStamp++;
Node newNode = new Node(id);
if(root==null){
root = newNode;
}
Node current = root;
Node parent = null;
while(true){
parent = current;
if(id < current.data){
current = current.left;
if(current==null){
parent.left = newNode;
}
}else{
current = current.right;
if(current==null){
parent.right = newNode;
}
}
}
}
public static Node delete(int x, Node n){
timeStamp++;
if(n==null)
return n;
if(x == n.data){
if(n.left == null && n.right == null){
return null;
}else if(n.left == null){
n.right = delete(x, n.right);
return n;
}else if(n.right == null){
n.left = delete(x, n.left);
return n;
}else{
Node tempNode = findMin(n.right);
n.right = delete(tempNode.data, n.right);
n.data = tempNode.data;
return n;
}
}
if(x < n.data){
n.left = delete(x, n.left);
return n;
}else{
n.right = delete(x, n.right);
return n;
}
}
public static void display(Node root){
if(root!=null){
display(root.left);
System.out.print(" " + root.data);
display(root.right);
}
}
public static Node findMin(Node n){
if(n == null){
return null;
}
if(n.left == null){
return n;
}
return findMin(n.left);
}
public static int maxAge(){
int currentAge = 0;
currentAge = timeStamp - ts;
if(currentAge > maxTime)
maxTime = currentAge;
return maxTime;
}
public static void main(String [] arg){
MinHeap min = new MinHeap();
min.insert(1, ts = 0);
min.insert(2, ts = 1);
min.insert(3, ts = 2);
min.insert(4, ts = 4);
min.delete(1, root);
min.delete(2, root);
min.delete(3, root);
min.delete(4, root);
min.maxAge();
}
}
class Node{
int data;
Node left;
Node right;
public Node(int data){
this.data = data;
left = null;
right = null;
}
}
您的插入损坏。找到插入点后,您忘了打破,并且您没有检查键已经在树上的情况。
while (true) {
parent = current;
if (id < current.data) {
current = current.left;
if (current == null) {
parent.left = newNode;
// Break after insert
break;
}
} else if (id > current.data) {
current = current.right;
if (current == null) {
parent.right = newNode;
// Break after insert
break;
}
} else {
// Key exists.
break;
}
}