Python实现
class Skiplist:

def __init__(self):    self.head = Node()  # dummy headdef search(self, target: int) -> bool:    node = self.head    while node:        while node.right and node.right.val < target:            node = node.right        if node.right and node.right.val == target:            return True        node = node.down  # 这一层没有，往下一层    return Falsedef add(self, num: int) -> None:    nodes = []    node = self.head    while node:        # Move to the right in the current level        while node.right and node.right.val < num:            node = node.right        nodes.append(node)        # Move to the next level        node = node.down    insert = True    down = None    while insert and nodes:        node = nodes.pop()        node.right = Node(num, node.right, down)        down = node.right        insert = (random.getrandbits(1) == 0)    # Create a new level with a dummy head    # right = None    # down = current head    if insert:        self.head = Node(-1, None, self.head)def erase(self, num: int) -> bool:    node = self.head    found = False    while node:        # Move to the right in the current level        while node.right and node.right.val < num:            node = node.right        # Find the target node        if node.right and node.right.val == num:            # Delete by skipping            node.right = node.right.right            found = True        # Move to the next level        node = node.down    return found

class Node:

def __init__(self, val=-1, right=None, down=None):    self.val = val    self.right = right    self.down = down

Your Skiplist object will be instantiated and called as such:

obj = Skiplist()

param_1 = obj.search(target)

obj.add(num)

param_3 = obj.erase(num)

Java实现
class Skiplist {

class Node {    int val;    Node right;    Node down;    Node(){        this(-1, null, null);    }    Node(int val, Node right, Node down) {        this.val = val;        this.right = right;        this.down = down;    }}Node head;public Skiplist() {    this.head = new Node();}public boolean search(int target) {    Node node = head;    while(node != null) {        while(node.right != null && node.right.val < target)            node = node.right;        if(node.right != null && node.right.val == target)            return true;        node = node.down;    }    return false;}public void add(int num) {    Node node = head;    LinkedList<Node> nodes = new LinkedList<>();    while(node != null) {        while(node.right != null && node.right.val < num) {            node = node.right;        }        nodes.add(node);        node = node.down;    }    // 向上回溯，[货币代码](https://www.gendan5.com/currencycode.html)依据概率判断是否新增节点    boolean isInsert = true;    // 最上面一层 100% 要新增    double c = 1.0;    Node down = null;           // 记录一下上面一层的down指针    while (!nodes.isEmpty() && isInsert) {        Node cur = nodes.removeLast();        cur.right = new Node(num, cur.right, down);        down = cur.right;        isInsert = count(c++);    }    if(isInsert)        this.head = new Node(-1, null, head);}public boolean erase(int num) {    Node node = head;    boolean res = false;    while(node != null) {        while(node.right != null && node.right.val < num) {            node = node.right;        }        if(node.right != null && node.right.val == num) {            res = true;            node.right = node.right.right;        }        node = node.down;    }    return res;}// 计算概率static boolean count(double i) {    double x = new Random().nextDouble();    double y = 1 / Math.pow(2, i);    return x <= y;}

}