Python常见算法实现：选择、快速、二分查找、广度优先与贪婪算法

#找到最小的元素def FindSmall(list):
  min=list[0]  for i in range(len(list)):    if list[i]<min:
      min=list[i]  return min    

#选择排序def Select_Sort(list):
  newArr=[]  for i in range(len(list)):
    minValue=FindSmall(list)
    newArr.append(minValue)
    list.remove(minValue)  return newArr

testArr=[11,22,33,21,123]print(Select_Sort(testArr))

def Quick_Sort(list):  if len(list)<2:    return list  else:
    temp=list[0]
    less=[i for i in list[1:] if i<=temp]
    more=[i for i in list[1:] if i>temp]    return Quick_Sort(less)+[temp]+Quick_Sort(more)

testArr= [13,44,53,24,876,2]print(Quick_Sort(testArr))

def Item_Search(list,item):
  low=0
  high=len(list)-1  while low<=high:
    middle=(low+high)//2    print(list[middle])    if list[middle]>item:
      high=middle-1    elif list[middle]<item:
      low=middle+1    else:      return middle  return None    

test_list=[1,3,5,7,9,11,13,15,17,19,21]
Item_Search(test_list,11)

#使用字典构建图graph={}
graph["you"]=["Alice","Bob","Claire"]
graph["Bob"]=["Anuj","Peggy"]
graph["Alice"]=["Peggy"]
graph["Claire"]=["Tom","Jonny"]
graph["Anuj"]=[]
graph["Peggy"]=[]
graph["Tom"]=[]
graph["Jonny"]=[]from collections import deque#简单的判断方法def person_is_seller(name):  return name=='Tom'def Search(name):
  searched=[]  #用于记录检查过的人，防止进入死循环
  search_queue=deque() #创建队列
  search_queue+=graph[name]  while search_queue:
    person=search_queue.popleft()    if not person in searched:  #仅当这个人没检查过时才检查
      if person_is_seller(person):        print("the seller is {0}".format(person))        return True      else:
        search_queue+=graph[person]
        searched.append(person)  #将这个人标记为检查过
  return Falseprint(Search("you"))

fruits=set(["苹果","香蕉","梨子","西瓜","草莓","橘子","荔枝","榴莲"]) 

#箱子以及包含的水果box={}
box["b1"]=set(["苹果","香蕉","西瓜"])
box["b2"]=set(["草莓","橘子","榴莲"])
box["b3"]=set(["梨子","荔枝","草莓"])
box["b4"]=set(["香蕉","橘子"])
box["b5"]=set(["梨子","榴莲"])

final_boxs=set() #最终选择的箱子#直到fruits为空while fruits:
  best_box=None #包含了最多的未包含水果的箱子
  fruits_covered=set() #包含该箱子包含的所有未包含的水果

  #循环迭代每个箱子，并确定它是否为最佳箱子
  for boxItem,fruitItem in box.items():
    covered=fruits & fruitItem #计算交集
    if len(covered)>len(fruits_covered): 
      best_box=boxItem
      fruits_covered=covered
  fruits-=fruits_covered
  final_boxs.add(best_box)   
print(final_boxs)