Sample solution

ticket_line.py

from collections import deque

# defines a type of "object", that represents a ticket-seeking visitor
class Visitor:
    # stores how many tickets the visitor needs
    needs = 0
    # stores how many tickets the visitor has
    has = 0
    # defines method to create a new visitor
    def __init__(self, needs):
        self.needs = needs
        self.has = 0
    # defines method to buy ticket, returns (outputs) whether they have enough now
    def buy(self):
        self.has += 1
        return self.hasEnough()
    # defines method to check if visitor has enough tickets
    def hasEnough(self):
        return self.has >= self.needs

def waitingTime(tickets, p):
    # track visitor needs
    visitors = [ Visitor(n) for n in tickets ]
    numVisitors = len(tickets)
    # queue represents the ticket line as a doubly-linked list
    queue = deque( range(numVisitors) )
    
    # track time units
    t = 0
    # run ticket queue until alex has enough tickets
    while not visitors[p].hasEnough():
        # increment time counter by one unit
        t += 1
        # remove leftmost (front) visitor from the line, grab visitor num
        cur = queue.popleft()
        # give visitor one extra ticket
        # if they still need more, add to back of the line
        if not visitors[cur].buy():
            queue.append(cur)
            
    # output how long it took alex to get their tickets
    return t

ticket_line_nocomments.py

from collections import deque

class Visitor:
    needs = 0
    has = 0
    
    def __init__(self, needs):
        self.needs = needs
        self.has = 0
    def buy(self):
        self.has += 1
        return self.hasEnough()
    def hasEnough(self):
        return self.has >= self.needs

def waitingTime(tickets, p):
    visitors = [ Visitor(n) for n in tickets ]
    numVisitors = len(tickets)
    queue = deque( range(numVisitors) )
    
    t = 0
    while not visitors[p].hasEnough():
        t += 1
        cur = queue.popleft()
        if not visitors[cur].buy():
            queue.append(cur)
            
    return t