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Commit9e239ad

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author
shengshijun
committed
带权选择活动.
1 parent754e8e1 commit9e239ad

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4 files changed

+92
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4 files changed

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‎README.md

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4. 加权有向无环图中最短路径和最长路径
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###幂乘：算法复杂度是O(lgn)
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##贪心算法
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1. 活动选择问题
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2. 顶点作色问题
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3. 带权活动选择问题(其实就是一个调度问题）
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###斐波那契树
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1. 使用循环实现的算法o(n)

‎dynamic/task/__init__.py

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#!/usr/bin/env python
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# -*- coding:UTF-8
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__author__='shenshijun'

‎dynamic/task/max_weighted_action.py

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#!/usr/bin/env python
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# -*- coding:UTF-8
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__author__='shenshijun'
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"""
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动态规划实现活动调度的问题，每个活动都有开始和结束时间，并且有一个权，要求得使得权和最大的活动集合
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"""
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classAction(object):
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"""
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活动对象
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"""
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def__init__(self,start_time,end_time,weight):
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self.start_time=start_time
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self.end_time=end_time
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self.weight=weight
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def__cmp__(self,other):
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pass
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def__eq__(self,other):
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returnself.start_time==other.start_timeandself.end_time==other.end_time
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def__hash__(self):
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returnhash(hash(self.start_time)*hash(self.end_time))
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def__str__(self):
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return"".join(["Action(start_time=",str(self.start_time),",ent_time=",str(self.end_time),",weight=",
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str(self.weight),")"])
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__value_dict= {}
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__actions_dict= {}
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defmax_weighted_actions(action_list):
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"""
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假设Action是按照end_time排序的。因此在算法里面就不排序了。
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:param action_list:
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:return:
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"""
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global__actions_dict
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global__value_dict
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action_len=len(action_list)
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# 循环退出条件
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ifaction_lenis0:
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return0
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cur_max_weight=0
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forkinxrange(action_len):
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left_max_weight=0
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ifk>0:
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if (action_list[0],action_list[k])notin__value_dict:
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__value_dict[(action_list[0],action_list[k])]=max_weighted_actions(
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filter(lambdaaction:action.end_time<=action_list[k].start_time,action_list[:k]))
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left_max_weight=__value_dict[(action_list[0],action_list[k])]
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right_max_weight=0
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ifk<action_len-1:
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if (action_list[k],action_list[-1])notin__value_dict:
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__value_dict[(action_list[k],action_list[-1])]=max_weighted_actions(
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filter(lambdaaction:action.start_time>=action_list[k].end_time,action_list[k+1:]))
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right_max_weight=__value_dict[(action_list[k],action_list[-1])]
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cur_weight=left_max_weight+right_max_weight+action_list[k].weight
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ifcur_max_weight<cur_weight:
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cur_max_weight=cur_weight
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__value_dict[(action_list[0],action_list[-1])]=cur_max_weight
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return__value_dict[(action_list[0],action_list[-1])]
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defmain():
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action_list= [Action(1,4,2),Action(3,5,1),Action(0,6,1),Action(5,7,2),Action(3,9,1),Action(5,9,1),
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Action(6,10,1),Action(8,11,2),Action(8,12,1),Action(2,14,1),Action(2,16,2)]
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print(max_weighted_actions(action_list))
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if__name__=="__main__":
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main()
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‎greedy/__init__.py

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#!/usr/bin/env python
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# -*- coding:UTF-8
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__author__='shenshijun'

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