秘密圣诞老人计划

Question

We are required to create a program that can be used for the game "Secret Santa":

from random import *
people=[]
while True:
    person=input("Enter a person participating.(end to exit):\n")
    if person=="end": break
    people.append(person)


shuffle(people)
for i in range(len(people)//2):
    print(people[0],"buys for",people[1])

Here is the program I developed. As of right now, if I input 3 people (Ex. Bob, Ben, Bill) it will return "Ben buys for Bill" with no one buying for Ben or Bob. I am currently trying to get it to output "Bob buys for Ben, Ben Buys for Bill, Bill buys for Bob" but have had no success thus far. If someone could give me a hint/basis for setting this up it would be greatly appreciated. Also, if there are any errors in my code that are not allowing me to accomplish this, can you let me know? Thanks.

Answer 1

First hint, it makes no sense to use constants like 0 and 1 instead of i inside your for loop.

for i in range(len(people)):
    print(people[i],"buys for",people[(i+1)%(len(people))])

However, this implementation will not give you all the possibilities offered by a Secret Santa.

Let's suppose you enter "Alice", "Bob", "Claire", "David", you'll never get to the situation where:

• Alice buys for Bob
• Bob buys for Alice
• Claire buys for David
• David buys for Claire

You will only get circular permutations , ie:

• Alice buys for Bob
• Bob buys for Claire
• Claire buys for David
• David buys for Alice

and alike.

You need some extra work to make a perfect Secret Santa :)

Answer 2

You are indexing 0 and 1, so it's always the first and second person being printed. What you really want is:

shuffle(people)
offset = [people[-1]] + people[:-1]
for santa, receiver in zip(people, offset):
     print(santa, "buys for", receiver)

Answer 3

Say you have three people: ['Bob', 'Ben', 'Bill'] .

In [1]: people = ['Bob', 'Ben', 'Bill']

Right now, when you get the length of this list, you're doing floor-division by 2. This results in:

In [2]: len(people) // 2
Out[2]: 1

That's why you only get a single line of output.

How might you get the Secret Santa result you want? Here are some hints for an easy way to implement this:

• You'll need some way of making sure two people don't get assigned to the same person and that a person doesn't get assigned to him- or herself.
• That probably means a list of possible buyers and a list of possible recipients -- pull them off one by one and find matches for them, checking that people aren't being assigned to themselves.

Answer 4

from random import *

prompt = "Enter a person participating.(end to exit):\n"
people = list(iter(lambda:input(prompt), "end"))

shuffle(people)
people.append(people[0])
for i in range(len(people) - 1):
    print(people[i],"buys for", people[i + 1])

Sample Run

Enter a person participating.(end to exit):
A
Enter a person participating.(end to exit):
B
Enter a person participating.(end to exit):
C
Enter a person participating.(end to exit):
end
A buys for B
B buys for C
C buys for A

You can replace

people=[]
while True:
    person=input("Enter a person participating.(end to exit):\n")
    if person=="end": break
    people.append(person)

with

prompt = "Enter a person participating.(end to exit):\n"
people = list(iter(lambda:input(prompt), "end"))

They both are doing the same thing. iter function will keep executing the function we pass as the first parameter, till the second value is matched.

And then, you do this

people.append(people[0])

Its a circular thing and the last person has to buy for the first person. append will insert at the last.

for i in range(len(people) - 1):

We do len(people) - 1 , because if there are n people, there will be n buyings. In this case, we have added the first person at the last, so we subtract one. Finally

print(people[i],"buys for", people[i + 1])

every person has to buy for the next person in the list. So, people[i] buys for the people[i + 1] .

Answer 5

I realize my answer is a bit late, here is my own secret santa project I have been using the past few years and my answer might help. I snipped out the important pieces from my script.

def pick_recipient(group,recipients,single_flag):
        for person in group:
                gift = random.choice(recipients)
                if single_flag == 0:
                        while gift in group:
                                gift = random.choice(recipients)
                else:
                        while gift in person:
                                gift = random.choice(recipients)
                mail_list.append( '%s=%s' %(person,gift))
                recipients.remove(gift)
        return recipients

if __name__ == "__main__":
        global mail_list
        mail_list = []

        #create lists of people, group couples at beginning or end of list and the singles opposite
        all_recipients = ['name_1-CoupleA: name_1-CoupleA@gmail.com','name_2-CoupleA: name_2-CoupleA@gmail.com',
                'name_3-CoupleB: name_3-CoupleB@hotmail.com','name_4: name_4CoupleB@hotmail.com',
                'name_5-Single: name_5-Single@gmail.com','name_6-Single: name_6-Single@gmail.com']

        #create couples and lists of singles to make sure couples don't get their other half
        #modify the groups to match the list of people from above
        coupleA = all_recipients [0:2]
        coupleB = all_recipients [2:4]
        single = all_recipients [4:]

        #keep initial list in tact      
        possible_recipients = all_recipients

        #modify the groups to match what the input list is
        possible_recipients = pick_recipient(coupleA,possible_recipients,single_flag=0)
        possible_recipients = pick_recipient(coupleB,possible_recipients,single_flag=0)
        possible_recipients = pick_recipient(single,possible_recipients,single_flag=1)

        print mail_list

Answer 6

secret-santa-finder

https://github.com/savitojs/secret-santa-finder-script

To use this script, you need to add name of the candidates you're playing with in secret_santa.py file. _from and _to lists should be same for better results.

Change _from and _to list(s)

To run

 $ ./secret_santa.py Hi.. What is your nick name? [ENTER] savsingh Hey savsingh!, Hold on!! Searching... Any guess... ? Your secret santa is: bar Clear the screen [ENTER]: 

So on...

Script here:

 #!/usr/bin/python #=============================================================================== # # FILE: secret_santa.py # # USAGE: ./secret_santa.py # # DESCRIPTION: It can help you to find your secret santa, add participants name in _from and _to list # # REQUIREMENTS: python 2.6+, _from list and _to list should be same to work perfectly. # AUTHOR: Savitoj Singh (savitojs@gmail.com) # VERSION: 1.1 # CREATED: 12/21/2016 05:13:38 AM IST # REVISION: * Initial release # * Fixed minor bugs #=============================================================================== import random import os import time import sys '''Add participants to list''' _from = ['bob','foo','bar','savsingh','tom','jack','mac','hex'] '''Add participants to list''' _to = ['bob','foo','bar','savsingh','tom','jack','mac','hex'] class bcolors: HEADER = '\\033[95m' OKBLUE = '\\033[94m' OKGREEN = '\\033[92m' WARNING = '\\033[93m' FAIL = '\\033[91m' ENDC = '\\033[0m' BOLD = '\\033[1m' UNDERLINE = '\\033[4m' for i in range(len(_from)): try: user_name = raw_input('Hi.. What is your nick name? [ENTER] ') if user_name not in _from and user_name not in _to: try: print("") print(bcolors.FAIL + bcolors.BOLD + "Nick name doesn't seem to be in `_from` or `_to` list" + bcolors.ENDC) print(bcolors.HEADER + "\\nDo you expect me to look in galaxy ? It may take many x'mas to retrive results :P" + bcolors.ENDC) break except: pass else: print('Hey ' + bcolors.OKBLUE + bcolors.BOLD + str(user_name) + bcolors.ENDC + '!, Hold on!! Searching...') random.shuffle(_from) _from.remove(user_name) print(bcolors.WARNING + 'Any guess... ?' + bcolors.ENDC) print('') time.sleep(1) a = random.choice(_to) while str(a) == str(user_name): a = random.choice(_to) _to.remove(a) print(bcolors.BOLD + 'Your secret santa is: ' + bcolors.ENDC + bcolors.OKGREEN + bcolors.BOLD + str(a) + bcolors.ENDC) raw_input('Clear the screen [ENTER]: ') os.system('reset') except: print(bcolors.FAIL + bcolors.BOLD + "\\n\\nOops!!, Something went wrong..." + bcolors.ENDC) sys.exit(1)