Use the Groupon API, and this API key (ee7ef79a62fc7685ac2ef382c7a9ef885a3035d0) to create an application with an auto-complete search box for merchant name and a location box. The locations supported in the location box could be an address that you geocode to a lat/long to center the search or could be a dropdown with the list of cities Groupon has deals in (the API supports both City and lat/long searches). Your app will fetch the deals for the location and build a dictionary on a per merchant basis to support the auto-complete feature in the search box.

For example, if the consumer selects "St. Louis" and types "Pizze" they should see the suggestions for "Pizzeria Roma", "Pizzeria Scillia", and "Pizzeria Uno" (provided those local restaurants were running deals returned by the Groupon API). As an additional challenge, have your auto-complete algorithm take distance into account and order the list of merchants by distance from the consumers search location instead of alphabetically.