“约瑟夫 - 问题”使用Python中列表(“Josephus-p‌r‌o‌b‌l‌e‌m” usi

2019-07-31 14:44发布

我想知道这是否是能够解决使用Python列表中的Josepheus问题。

简单来说约瑟夫问题是所有有关查找以圆形布置的位置,如果执行使用该事先已知的跳过参数处理出这将是安全的。

为例如:给定一个圆形布置如[1,2,3,4,5,6,7]和3跳过参数,人们会在顺序执行的3,6,2,7,5,1和位置4将是安全的。

我一直在努力,现在解决这个名单使用了一段时间,但该指数位置变得棘手,我来处理。

 a=[x for x in range(1,11)]
 skip=2
 step=2
 while (len(a)!=1):
   value=a[step-1]
   a.remove(value)
   n=len(a)
   step=step+skip
   large=max(a)
   if step>=n:        
      diff=abs(large-value)
      step=diff%skip
   print a

更新了代码段的问题,但我不认为我的逻辑是正确的。

Answer 1:

很简单,你可以使用list.pop(i)删除每一个受害者(并得到他的ID)在一个循环。 然后,我们就不必担心包裹指数,你可以通过采取跳过率MOD剩余囚犯人数只是做。

那么,问题的解决方案变得

def josephus(ls, skip):
    skip -= 1 # pop automatically skips the dead guy
    idx = skip
    while len(ls) > 1:
        print ls.pop(idx) # kill prisoner at idx
        idx = (idx + skip) % len(ls)
    print 'survivor: ', ls[0]

测试输出:

>>> josephus([1,2,3,4,5,6,7], 3)
3
6
2
7
5
1
survivor:  4


Answer 2:

In [96]: def josephus(ls, skip):
    ...:     from collections import deque
    ...:     d = deque(ls)
    ...:     while len(d)>1:
    ...:         d.rotate(-skip)
    ...:         print(d.pop())
    ...:     print('survivor:' , d.pop())
    ...:     

In [97]: josephus([1,2,3,4,5,6,7], 3)
3
6
2
7
5
1
survivor: 4

如果你不想计算指数,可以使用deque的数据结构。



Answer 3:

它看起来更糟,但更容易理解,适合初学者

def last(n):
    a=[x for x in range(1,n+1)]
    man_with_sword = 1
    print(a)
    while len(a)!=1:   
        if man_with_sword == a[len(a)-2]:  #man_with_sword before last in circle
            killed = a[len(a)-1]
            a.remove(killed)
            man_with_sword=a[0]
        elif man_with_sword==a[len(a)-1]:  #man_with_sword last in circle
            killed = a[0]
            a.remove(killed)
            man_with_sword=a[0]
        else:
            i=0
            while i < (len(a)//2): 
                i=a.index(man_with_sword)
                killed = a[a.index(man_with_sword)+1]
                a.remove(killed)
                #pass the sword 
                man_with_sword=a[i+1] # pass the sword to next ( we killed next)
                print (a, man_with_sword) #show who survived and sword owner
                i+=1
        print (a, man_with_sword,'next circle') #show who survived and sword owner


Answer 4:

我的解决方案使用的数学技巧我在网上找到的位置: https://www.youtube.com/watch?v=uCsD3ZGzMgE它采用书面形式的人在圈内和数量,其中幸存者坐在位置的二进制方式。 结果是相同的,并且代码较短。

和代码是这样的:

numar_persoane = int(input("How many people are in the circle?\n")) #here we manually insert the number of people in the circle

x='{0:08b}'.format(int(numar_persoane)) #here we convert to binary

m=list(x) #here we transform it into a list

for i in range(0,len(m)): #here we remove the first '1' and append to the same list

    m.remove('1')

    m.append('1')

    break

w=''.join(m) #here we make it a string again

print("The survivor sits in position",int(w, 2)) #int(w, 2) makes our string a decimal number


Answer 5:

这是我解决你的问题:

# simple queue implementation<ADT>
class Queue:
    def __init__(self):
        self.q = []
    def enqueue(self,data):
        self.q.insert(0,data)
    def dequeue(self):
        self.q.pop()
    def sizeQ(self):
        return len(self.q)
    def printQ(self):
        return self.q


lists = ["Josephus","Mark","Gladiator","Coward"]
to_die = 3
Q = Queue()
# inserting element into Q
for i in lists:
    Q.enqueue(i)
# for size > 1 
while Q.sizeP() > 1:
    for j in range(1,3): 
# every third element to be eliminated
         Q.enqueue(Q.dequeue())
    Q.dequeue()
print(Q.printQ())


Answer 6:

def Last_Person(n):
    person = [x for x in range(1,n+1)]
    x = 0
    c = 1
    while len(person) > 1:
        if x == len(person) - 1:
            print("Round ", c, "- Here's who is left: ", person, "Person ", person[x], "killed person", person[0])
            person.pop(0)
            x = 0
            c = c+1
        elif x == len(person) - 2:
            print("Round ", c, "- Here's who is left: ", person, "Person ", person[x], "killed person", person[x + 1])
            person.pop(x+1)
            x = 0
            c = c + 1
        else:
            print("Round ", c, "- Here's who is left: ", person, "Person ", person[x], "killed person", person[x + 1])
            person.pop(x + 1)
            x = x + 1
            c = c + 1
    print("Person", person[x], "is the winner")

Last_Person(50)


文章来源: “Josephus-p‌r‌o‌b‌l‌e‌m” using list in python