algorithm-in-python/dataStructure/loserTree.py
2019-01-31 12:09:46 +08:00

117 lines
3.5 KiB
Python

''' mbinary
#########################################################################
# File : loserTree.py
# Author: mbinary
# Mail: zhuheqin1@gmail.com
# Blog: https://mbinary.xyz
# Github: https://github.com/mbinary
# Created Time: 2018-05-19 23:06
# Description:
#########################################################################
'''
from winnerTree import winnerTree
class loserTree:
'''if i<=lowExt p = (i+offset)//2
else p = (i+n-1-lowExt)//2
s is the num of the full subtree node
p is the index of tree
i is the index of players
offset is a num 2^k-1 just bigger than n
lowExt is the double node num of the lowest layer of the tree
'''
def __init__(self,players,reverse=False):
self.n=len(players)
self.tree = [0]*self.n
players.insert(0,0)
self.players=players
self.reverse=reverse
self.getNum()
self.tree[0] = self.initTree(1)
self.dir=None
def getNum(self):
i=1
while 2*i< self.n:i=i*2
if 2*i ==self. n:
self.lowExt=0
self.s = 2*i-1
else:
self.lowExt = (self.n-i)*2
self.s = i-1
self.offset = 2*i-1
def treeToArray(self,p):
return 2*p-self.offset if p>self.s else 2*p+self.lowExt-self.n+1
def arrayToTree(self,i):
return (i+self.offset)//2 if i<=self.lowExt else (i-self.lowExt+ self.n-1)//2
def win(self,a,b):
return a<b if self.reverse else a>b
def initTree(self,p):
if p>=self.n:
delta = p%2 #!!! good job notice delta mark the lchild or rchlid
return self.players[self.treeToArray(p//2)+delta]
l = self.initTree(2*p)
r = self.initTree(2*p+1)
if self.win(r,l):
self.tree[p] = l
self.dir = 'r'
return r
else :
self.tree[p] = r
self.dir = 'l'
return l
def getWinIdx(self,idx=1):
while 2*idx<self.n:
idx = 2*idx if self.tree[idx].dir == 'l' else idx*2+1
return self.treeToArray(idx)
def winner(self):
i = self.getWinIdx()
i = i+1 if self.players[i] !=self.tree[0] else i
return self.tree[0],i
def getOppo(self,i,x,p):
oppo=None
if 2*p<self.n:oppo=self.tree[2*p]
elif i<=self.lowExt:oppo=self.players[i-1+i%2*2]
else:
lpl= self.players[2*p+self.lowExt-self.n+1]
oppo = lpl if lpl!=x else self.players[2*p+self.lowExt-self.n+2]
return oppo
def update(self,i,x):
''' i is 1-indexed which is the num of player
and x is the new val of the player '''
self.players[i]=x
p = self.arrayToTree(i)
oppo =self.getOppo(i,x,p)
self.tree[p],winner = x , oppo if self.win(oppo,x) else oppo,x
p=p//2
while p:
l = self.tree[p*2]
r = None
if 2*p+1<self.n:r=self.tree[p*2+1] #notice this !!!
else:r = self.players[2*p+self.lowExt-self.n+1]
self.tree[p] = l if self.win(l,r) else r
p=p//2
# to do update-func the change of every node's dir and loser
if __name__ =='__main__':
s= [4,1,6,7,9,5234,0,2,7,4,123]
t = winnerTree(s)
for i in s:
val,idx=t.winner()
print(val,idx)
t.update(idx,-1)
'''
[0, 4, 1, 6, 7, 9, 5234, 0, 2, 123] [0, 5234, 9, 5234, 6, 9, 5234, 123, 4]
5234 6
123 9
9 5
7 4
6 3
4 1
2 8
1 2
0 7
-1 1
'''