Maximum Fenwick Tree More info: https:cpalgorithms.comdatastructuresfenwick.html   ft  MaxFenwickTree5  ft.query0, 5 0  ft.update4, 100  ft.query0, 5 100  ft.update4, 0  ft.update2, 20  ft.query0, 5 20  ft.update4, 10  ft.query2, 5 20  ft.query1, 5 20  ft.update2, 0  ft.query0, 5 10  ft  MaxFenwickTree10000  ft.update255, 30  ft.query0, 10000 30  ft  MaxFenwickTree6  ft.update5, 1  ft.query5, 6 1  ft  MaxFenwickTree6  ft.update0, 1000  ft.query0, 1 1000 Create empty Maximum Fenwick Tree with specified size Parameters: size: size of Array Returns: None Get next index in O1 Get previous index in O1 Set index to value in Olg2 N Parameters: index: index to update value: value to set Returns: None Answer the query of maximum range l, r in Olg2 N Parameters: left: left index of query range inclusive right: right index of query range exclusive Returns: Maximum value of range left, right
class MaxFenwickTree:
    """
    Maximum Fenwick Tree

    More info: https://cp-algorithms.com/data_structures/fenwick.html
    ---------
    >>> ft = MaxFenwickTree(5)
    >>> ft.query(0, 5)
    0
    >>> ft.update(4, 100)
    >>> ft.query(0, 5)
    100
    >>> ft.update(4, 0)
    >>> ft.update(2, 20)
    >>> ft.query(0, 5)
    20
    >>> ft.update(4, 10)
    >>> ft.query(2, 5)
    20
    >>> ft.query(1, 5)
    20
    >>> ft.update(2, 0)
    >>> ft.query(0, 5)
    10
    >>> ft = MaxFenwickTree(10000)
    >>> ft.update(255, 30)
    >>> ft.query(0, 10000)
    30
    >>> ft = MaxFenwickTree(6)
    >>> ft.update(5, 1)
    >>> ft.query(5, 6)
    1
    >>> ft = MaxFenwickTree(6)
    >>> ft.update(0, 1000)
    >>> ft.query(0, 1)
    1000
    """

    def __init__(self, size: int) -> None:
        """
        Create empty Maximum Fenwick Tree with specified size

        Parameters:
            size: size of Array

        Returns:
            None
        """
        self.size = size
        self.arr = [0] * size
        self.tree = [0] * size

    @staticmethod
    def get_next(index: int) -> int:
        """
        Get next index in O(1)
        """
        return index | (index + 1)

    @staticmethod
    def get_prev(index: int) -> int:
        """
        Get previous index in O(1)
        """
        return (index & (index + 1)) - 1

    def update(self, index: int, value: int) -> None:
        """
        Set index to value in O(lg^2 N)

        Parameters:
            index: index to update
            value: value to set

        Returns:
            None
        """
        self.arr[index] = value
        while index < self.size:
            current_left_border = self.get_prev(index) + 1
            if current_left_border == index:
                self.tree[index] = value
            else:
                self.tree[index] = max(value, current_left_border, index)
            index = self.get_next(index)

    def query(self, left: int, right: int) -> int:
        """
        Answer the query of maximum range [l, r) in O(lg^2 N)

        Parameters:
            left: left index of query range (inclusive)
            right: right index of query range (exclusive)

        Returns:
            Maximum value of range [left, right)
        """
        right -= 1  # Because of right is exclusive
        result = 0
        while left <= right:
            current_left = self.get_prev(right)
            if left <= current_left:
                result = max(result, self.tree[right])
                right = current_left
            else:
                result = max(result, self.arr[right])
                right -= 1
        return result


if __name__ == "__main__":
    import doctest

    doctest.testmod()
