from datetime import time
from pprint import pprint

visitors = [
    {
        'id': 10,
        'start_time': time(9, 10),
        'end_time': time(13, 5),
        'conflicts_with': []
    },
    {
        'id': 15,
        'start_time': time(14, 0),
        'end_time': time(14, 26),
        'conflicts_with': []
    },
    {
        'id': 20,
        'start_time': time(14, 20),
        'end_time': time(15, 15),
        'conflicts_with': []
    },
    {
        'id': 30,
        'start_time': time(14, 25),
        'end_time': time(14, 30),
        'conflicts_with': []
    },
    {
        'id': 40,
        'start_time': time(15, 0),
        'end_time': time(17, 0),
        'conflicts_with': []
    }
]


active_visitors = []

for v in visitors:
    for a in active_visitors.copy():
        if v['start_time'] < a['end_time']:
            a['conflicts_with'].append(v['id'])
            v['conflicts_with'].append(a['id'])
        else:
            active_visitors.remove(a)

    active_visitors.append(v)


for v in sorted(visitors, key=lambda x: len(x['conflicts_with']), reverse=True):
    if len(v['conflicts_with']):
        for _id in v['conflicts_with']:
            another_cand = [x for x in visitors if x['id'] == _id][0]
            another_cand['conflicts_with'].remove(v['id'])

        visitors.remove(v)

print(len(visitors))

import random
from datetime import datetime, timedelta


def func(visitors):
    active_visitors = []

    for ind in sorted(visitors):
        v = visitors[ind]
        for ind_a in active_visitors.copy():
            active_visitor = visitors[ind_a]

            if v['start_time'] < active_visitor['end_time']:
                active_visitor['conflicts_with'].append(ind)
                v['conflicts_with'].append(ind_a)
            else:
                active_visitors.remove(ind_a)

        active_visitors.append(ind)

    for ind in sorted(visitors, key=lambda x: len(visitors[x]['conflicts_with']), reverse=True):
        v = visitors[ind]

        if len(v['conflicts_with']):
            for _id in v['conflicts_with']:
                another_cand = visitors[_id]
                another_cand['conflicts_with'].remove(ind)

            del visitors[ind]


def gen_time_pairs():
    total_seconds = 9 * 60 * 60  # 32400 seconds between 9:00-18:00
    nine_o_clock = datetime(2019, 1, 21, 9, 0)

    time_pairs = []
    for _ in range(1000):
        t1 = random.randint(0, total_seconds)
        t2 = random.randint(0, total_seconds)

        assert t1 != t2, 'test data failed, re-run script'

        if t1 > t2:
            t1, t2 = t2, t1

        start_time = nine_o_clock + timedelta(seconds=t1)
        end_time = nine_o_clock + timedelta(seconds=t2)

        time_pairs.append((start_time, end_time))

    return time_pairs


def gen_visitors(time_pairs):
    res_visitors = {}
    ind = 0

    for start_time, end_time in sorted(time_pairs, key=lambda x: x[0]):
        res_visitors[ind] = {
            'start_time': start_time,
            'end_time': end_time,
            'conflicts_with': []
        }
        ind += 1

    return res_visitors

time_pairs = gen_time_pairs()
visitors = gen_visitors(time_pairs)
func(visitors)

print(len(visitors))