python版线段树

</pre><pre name="code" class="python">#coding=gbk
#线段树
class Tree(object):
def __init__(self,l,r):
self.l = l
self.r = r
self.value = 0
self.left = None
self.right = None
if l < r:
mid = (l + r)/2
self.left = Tree(l,mid)
self.right = Tree(mid+1,r)

def set_value(self,p,value):
if self.l == self.r:
self.value = value
return
mid = (self.l + self.r)/2
if p <= mid:
self.left.set_value(p,value)
else:
self.right.set_value(p,value)
self.push_up()

def push_up(self):
self.value = self.left.value + self.right.value

def query(self,x,y):
print "query",x,y,'\t',(self.l + self.r)/2,'\t',self.l,self.r,self.value
if x <= self.l and y>=self.r:
return self.value
if self.l == self.r:
return self.value

mid = (self.l + self.r)/2
if mid >= y:
return self.left.query(x,y)
elif mid < x:
return self.right.query(x,y)
else:
return self.left.query(x,mid) + self.right.query(mid+1,y)

def main():
N = 1024
import time
old =time.time()
tree = Tree(0,N)
for i in xrange(N+1):
# print i
tree.set_value(i,1)
print tree.query(30,60)
print time.time() -old

if __name__ == "__main__":
main()