A group of friends went to a party and purchased some food and drinks for that. Now they are trying to evenly split the total bill in an efficient way.

PartyBill

import random

numOfPeople = 8
amountScale = 100
init_amounts = [random.randrange(amountScale) for i in range(numOfPeople)]
# Real world example
init_amounts = [56.16, 0, 26.7, 14, 80.1, 225.98, 238.86/2, 238.86/2]
# print init_amounts

sorted_amounts = sorted(init_amounts, reverse=True)
# print init_amounts
print sorted_amounts

avg_amount = sum(sorted_amounts) / float(len(sorted_amounts))
# print avg_amount

excess_amount = [(i - avg_amount) for i in sorted_amounts]
print excess_amount

collection_pointer = 0
payment_pointer = len(sorted_amounts)-1

while collection_pointer < payment_pointer:
    if excess_amount[collection_pointer] > -excess_amount[payment_pointer]:
        print "Person {0} pays person {1} ${2}.".format(payment_pointer, collection_pointer, -excess_amount[payment_pointer])
        excess_amount[collection_pointer] = excess_amount[collection_pointer] + excess_amount[payment_pointer]
        payment_pointer = payment_pointer - 1
    elif excess_amount[collection_pointer] < -excess_amount[payment_pointer]:
        print "Person {0} pays person {1} ${2}.".format(payment_pointer, collection_pointer, excess_amount[collection_pointer])
        excess_amount[payment_pointer] = excess_amount[payment_pointer] + excess_amount[collection_pointer]
        collection_pointer = collection_pointer + 1
    else:
        print "Person {0} pays person {1} ${2}.".format(payment_pointer, collection_pointer, excess_amount[collection_pointer])
        payment_pointer = payment_pointer - 1
        collection_pointer = collection_pointer + 1