parthmittal

max_N = (1 << 20) #This is the maximum size of array our tree will support
seg = [0] * (4 * max_N) #Initialises the 'tree' to all zeroes.

def build(someList, v, L, R):
	global seg
	if (L == R):
		seg[v] = someList[L]
	else:
		mid = (L + R) / 2 #Integer division is equivalent to flooring.
		build(someList, 2 * v, L, mid)

parthmittal

class segment_tree:
	"""A class which implements a range sum tree"""

	def __init__(self, some_list):
		"""
		Initialises the tree, needs a list as a parameter
		"""
		
		self.N = len(some_list)
		self.seg = [0] * (4 * len(some_list))