AN IRISH SOFTWARE developer has come up with a timely mapping algorithm that solves a challenge made over a century ago in James Joyce’s most famous work.

In Ulysses – which, as luck would have it, was set on June 16, back in 1904 – the hero Leopold Bloom remarked that “a good puzzle would be to cross Dublin without passing a pub”.

While there are fewer pubs around Dublin now than there would have been back in Bloom’s Day, the challenge had stumped Dubliners and tourists alike for decades – but Rory McCann, 27, has managed to come up with a workable route.

McCann took an open-source OpenStreetMaps map of Dublin, which included the location of every pub in the city, and isolated 15 points around the Royal Canal circling Dublin’s northside, and another 15 on the Grand Canal circling the south.

Drawing lines between each opposing pair of entry points, McCann then programmed the map to see if any of the 15 journeys could be filled without passing any of Dublin’s watering holes – and, miraculously, came up with an answer.

There are a couple of caveats to his route: it does pass by a certain number of hotels with bars inside them, but these are not deemed ‘bars’ if they are not popularised by non-residents, while it also overlooks restaurants with alcohol licences.

But, to be totally sure of his route, the route was programmed to ensure that the route did not bring you within 35 metres of the pub (to ensure that you weren’t walking past a pub on the opposite side of a street).

The result? It’s possible to walk from Blackhorse to Baggot Street without passing a pub. The route takes you through Stoneybatter, St James’s Gate (ironically the site of Dublin’s best-known brewery!), down Bride Street, across York Street, past Stephen’s Green, detouring through the Iveagh Gardens, and down Adelaide Road.

It only took 39,079 days – but finally a famous Dublin riddle has been resolved.

McCann has not yet indicated whether he will now deploy the same algorithm to formulate Dublin’s most epic pub crawl.