talum

// return all combinations of array elements for size n
// ex) combinations([1,2,3], 2) => [[1,2], [2,3], [1,3]]

// use backtracking & recursion
// iteration: for each element
// add element
// recurse with element
// remove element
// continue

talum

/**
 * @param {number} numCourses
 * @param {number[][]} prerequisites
 * @return {number[]}
 */
var findOrder = function(numCourses, prerequisites) {
    let adjList = {};
    let indegree = {};
    let topologicalOrder = [];
    

talum

import React, { PureComponent } from 'react'
import PropTypes from 'prop-types'

import Button from 'lib/shared-react-components/buttons/Button'

export default class Ellipsis extends PureComponent {
  render () {
    if (!this.props.visible) return null

    return (

talum

defmodule Registrar.Billing.Invoice do
  # assume that we have an Ecto.Schema defined with all the fields this module needs to know about
  import Ecto.Changeset
  
  def changeset(%Invoice{} = invoice, attrs \\ %{}) do
    invoice
    |> cast(attrs, [
      :amount_due,
      :due_date,
      :scheduled_send_date

talum

defmodule Registrar.Billing.Invoice do
  import Ecto.Changeset

  def changeset(%Invoice{} = invoice, attrs \\ %{}) do
    invoice
    |> cast(attrs, [
      :amount_due,
      :due_date,
      :scheduled_send_date,
      :email

talum

defmodule Registrar.Billing.Invoice do
  import Ecto.Changeset

  def changeset(%Invoice{} = invoice, attrs \\ %{}) do
    invoice
    |> cast(attrs, [
      :amount_due,
      :due_date,
      :scheduled_send_date
      ])

talum

defmodule Registrar.Billing.Invoice do
  import Ecto.Changeset

  def mark_closed_changeset(%Invoice{} = invoice, attrs \\ %{}) do
    invoice
    |> cast(attrs, [
      :closed_at
      ])
    |> validate_required([
      :closed_at

talum

defmodule Registrar.Billing.Invoice do
  import Ecto.Changeset
  
  def mark_paid_changeset(%Invoice{} = invoice, attrs \\ %{}) do
    invoice
    |> cast(attrs, [
      :paid_at
      ])
    |> validate_required([
      :paid_at

talum

iex> attributes = %{amount_due: 3000, due_date: "2019-04-30", scheduled_send_date: "2019-04-25",
iex> closed_at: "2019-05-01"}
iex> changeset = Registrar.Billing.Invoice.changeset(%Invoice{}, attributes)
iex> #Ecto.Changeset<
  action: nil,
  changes: %{amount_due: 3000, due_date: ~D[2019-04-30], scheduled_send_date: ~D[2019-04-25]},
  errors: [],
  data: #Registrar.Billing.Invoice<>,
  valid?: true
>

talum

class InvoicesController < ApplicationController
  def update

    # The developer reasons that adding a timestamp to the params to
    # leverage the existing code will do the trick

    if params[:cancel]
      invoice_params[:closed_at] = Time.current
    end