Python/data_structures/binary_tree/fenwick_tree.py
Christian Clauss 89acf5d017 print() is a function just like every other function (#1101)
* print() is a function just like every other function
2019-08-06 12:14:23 +02:00

30 lines
770 B
Python

from __future__ import print_function
class FenwickTree:
def __init__(self, SIZE): # create fenwick tree with size SIZE
self.Size = SIZE
self.ft = [0 for i in range (0,SIZE)]
def update(self, i, val): # update data (adding) in index i in O(lg N)
while (i < self.Size):
self.ft[i] += val
i += i & (-i)
def query(self, i): # query cumulative data from index 0 to i in O(lg N)
ret = 0
while (i > 0):
ret += self.ft[i]
i -= i & (-i)
return ret
if __name__ == '__main__':
f = FenwickTree(100)
f.update(1,20)
f.update(4,4)
print(f.query(1))
print(f.query(3))
print(f.query(4))
f.update(2,-5)
print(f.query(1))
print(f.query(3))