Implementation of compressed 2D Binary Indexed tree – GeeksforGeeks

class Compressed2DBIT:

    def __init__(self, n, m):

        self.n = n

        self.m = m

        self.bit = [[0] * (m + 1) for _ in range(n + 1)]

        self.tree = None

    def update(self, x, y, val):

        while x <= self.n:

            y1 = y

            while y1 <= self.m:

                self.bit[x][y1] += val

                y1 += y1 & -y1

            x += x & -x

    def query(self, x, y):

        s = 0

        while x > 0:

            y1 = y

            while y1 > 0:

                s += self.bit[x][y1]

                y1 -= y1 & -y1

            x -= x & -x

        return s

    def compress(self):

        self.tree = [

            [0] * self.m for _ in range(self.n)]  

        for i in range(1, self.n + 1):

            for j in range(1, self.m + 1):

                self.tree[i-1][j-1] = self.query(i, j) - self.query(

                    i-1, j) - self.query(i, j-1) + self.query(i-1, j-1)

        self.bit_compressed = None  

arr = [[1, 2, 3, 4, 5],

       [6, 7, 8, 9, 10],

       [11, 12, 13, 14, 15],

       [16, 17, 18, 19, 20]]

bit = Compressed2DBIT(4, 5)

for i in range(4):

    for j in range(5):

        bit.update(i + 1, j + 1, arr[i][j])

print(bit.query(2, 3)) 

print(bit.query(4, 5)) 

bit.compress()

print(bit.query(2, 3)) 

print(bit.query(4, 5)) 

print(bit.tree)