creddit/config/routes.rb

Rails.application.routes.draw do
  get 'signup', to: 'users#new', as: :signup
  get 'signin', to: 'user_sessions#new', as: :signin
  get 'signout', to: 'user_sessions#destroy', as: :signout

  resources :subcreddits, path: 'c', except: [:destroy] do
    resources :posts, path: '', constraints: { id: /\d+\-.+/ }, except: [:index] do
      resources :comments, path: '', constraints: { id: /\d+/ }, except: [:index]
    end
  end

  resources :user_sessions, only: [:new, :create, :destroy]
  resources :users, path: 'u', only: [:show, :new, :create]

  root to: 'subcreddits#index'
end