algorithm_for_read_to.sagews

# Given say {"a": 3, "b": 10, "c": 7, "d": 19} and [1,5,15] return {0: ["a"], 1: ["b", "c"], 2: ["d"]}
def find_read_to(read_dates, message_dates):
        read_indexes_to_user_ids = {}
        for user_id in read_dates:
                for i, date in enumerate(message_dates):
                        last_index = i + 1 == len(message_dates)
                        next_index = -1 if last_index else i + 1
                        if last_index or (read_dates[user_id] >= date and read_dates[user_id] < message_dates[next_index]):
                                if i in read_indexes_to_user_ids:
                                        read_indexes_to_user_ids[i].append(user_id)
                                else:
                                        read_indexes_to_user_ids[i] = [user_id]
                                break
        return read_indexes_to_user_ids

find_read_to({"a": 3, "b": 10, "c": 7, "d": 19}, [1,5,15])

{0: ['a'], 1: ['c', 'b'], 2: ['d']}

import bisect
def find_read_to(read_dates, message_dates):
        read_indexes_to_user_ids = {}
        user_ids, read_dates = zip(*read_dates.items())
        def find_between(read_date):
                answer = bisect.bisect_left(message_dates, read_date)
                answer -= 1
                if answer == -1:
                        return None
                return answer
        indexes_for_read_up_to = map(find_between, read_dates)
        for i, index_for_read_up_to in enumerate(indexes_for_read_up_to):
                user_id = user_ids[i]
                if index_for_read_up_to in read_indexes_to_user_ids:
                        read_indexes_to_user_ids[index_for_read_up_to].append(user_id)
                else:
                        read_indexes_to_user_ids[index_for_read_up_to] = [user_id]
        return read_indexes_to_user_ids

find_read_to({"a": 3, "b": 10, "c": 7, "d": 19}, [1,5,15])

{0: ['a'], 1: ['c', 'b'], 2: ['d']}

%coffee
underscore = require('underscore')
Array::bisect = (val) ->
    idx = undefined
    if @length == 0
        return 0
    idx = 0
    while idx < @length
        if val < @[idx]
            return idx
        idx++
    idx

find_read_tos = (read_dates, message_dates) ->
    read_indexes_to_user_ids = {}
    [user_ids, read_dates] = [Object.keys(read_dates), underscore.values(read_dates)]
    find_between = (read_date) ->
        answer = message_dates.bisect(read_date)
        answer -= 1
        if answer == -1
            return null
        return answer
    indexes_for_read_up_to = (find_between(date) for date in read_dates)
    for index_for_read_up_to, i in indexes_for_read_up_to
        user_id = user_ids[i]
        if index_for_read_up_to is null
            continue
        if String(index_for_read_up_to) in Object.keys(read_indexes_to_user_ids)
            read_indexes_to_user_ids[index_for_read_up_to].push(user_id)
        else
            read_indexes_to_user_ids[index_for_read_up_to] = [user_id]
    return read_indexes_to_user_ids

console.log(find_read_tos({"a": 3, "b": 10, "c": 7, "d": 19}, [1,5,15]))

{ '0': [ 'a' ], '1': [ 'b', 'c' ], '2': [ 'd' ] }

%coffee
array_bisect = (arr, val) ->
    idx = undefined
    if arr.length == 0
        return 0
    idx = 0
    while idx < arr.length
        if val < arr[idx]
            return idx
        idx++
    idx
console.log(array_bisect([0,3,5,15,30,90], 11))

3

coffee??

   File: /projects/d8eac431-3b55-40d3-89ee-fcada259f1ad
Unable to read source code (source code not available)

%coffee
find_smaller_number = (arr, val) ->
    idx = undefined
    if arr.length == 0
        return -1
    idx = 0
    while idx < arr.length
        if val < arr[idx]
            return idx - 1
        idx++
    idx - 1
console.log(find_smaller_number([], 9))

-1

%coffee
_ = require('underscore')
console.log(_.sortBy([5,3,9,1]))

[ 1, 3, 5, 9 ]