"Josephus-p‌r‌o‌b‌l‌e‌m" using list in python

Quite simply, you can use list.pop(i) to delete each victim (and get his ID) in a loop. Then, we just have to worry about wrapping the indices, which you can do just by taking the skipped index mod the number of remaining prisoners.

So then, the question solution becomes

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])

Test output:

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

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

If you do not want to calculate the index, you can use the deque data structure.

if you are looking for the final result only, here is a simple solution.

def JosephusProblem(people):
  binary = bin(people)  # Converting to binary
  winner = binary[3:]+binary[2]  # as the output looks like '0b101001'. removing 0b and adding the 1 to the end
  print('The winner is',int(winner,2))  #converting the binary  back to decimal

If you are looking for the math behind this code, go check out this video: Josephus Problem(youTube)

My solution uses a math trick I found online here: https://www.youtube.com/watch?v=uCsD3ZGzMgE It uses the binary way of writing the number of people in the circle and the position where the survivor sits. The result is the same and the code is shorter.

And the code is this:

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