2026-01-05 14:24:49 +0300 MSK

class Node:
    def __init__(
        self, 
        char: str, 
        prev: Optional["Node"], 
        nxt: Optional["Node"]
    ) -> None:
        self.char = char
        self.prev = prev
        self.nxt = nxt

class TextEditor:

    def __init__(self):
        self.length = 0
        self.root = Node("", None, None)
        self.cursor = self.root

    def addText(self, text: str) -> None:
        node = self.cursor
        self.length += len(text)
        for char in text:
            cur = Node(char, node, node.nxt)
            nxt = node.nxt
            node.nxt = cur
            if nxt:
                nxt.prev = cur
            node = cur
            self.cursor = cur

    def deleteText(self, k: int) -> int:
        res = 0
        while self.cursor is not self.root and k > 0:
            res += 1
            k -= 1
            if self.cursor.nxt:
                self.cursor.nxt.prev = self.cursor.prev
            self.cursor.prev.nxt = self.cursor.nxt
            self.cursor = self.cursor.prev
        return res

    def last_ten(self) -> str:
        res = []
        node = self.cursor
        while node is not self.root and len(res) < 10:
            res.append(node.char)
            node = node.prev
        res.reverse()
        return "".join(res)

    def cursorLeft(self, k: int) -> str:
        while self.cursor is not self.root and k > 0:
            k -= 1
            self.cursor = self.cursor.prev
        res = self.last_ten()
        return res

    def cursorRight(self, k: int) -> str:
        while self.cursor.nxt  and k > 0:
            k -= 1
            self.cursor = self.cursor.nxt
        res = self.last_ten()
        return res

# Your TextEditor object will be instantiated and called as such:
# obj = TextEditor()
# obj.addText(text)
# param_2 = obj.deleteText(k)
# param_3 = obj.cursorLeft(k)
# param_4 = obj.cursorRight(k)