@@ -0,0 +1,28 @@
+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))