diamond geezer

 Saturday, November 02, 2019

Today's post is about making a journey through tube stations whose names include every letter of the alphabet.

What's the shortest route which ticks off all 26 letters?

n.b. Tube stations only.
n.b. Route must pass through consecutive stations.
n.b. We're looking for the journey which passes through the fewest stations.
n.b. In case of a tie, the fewer trains the better.

For example, OVAL ticks off four different letters, KENNINGTON gets six more, but WATERLOO would only add another two. So that's not a great start.

The key to this challenge is knowing where the least frequent letters are.

In particular there's only one Z on the tube map, at BELSIZE PARK, so we're going to have to include that.

Hurrah, that's ten letters of the alphabet [ABEIKLPRSZ] sorted already.

No stations further up the Edgware branch of the Northern line have any interesting letters, so we need to head south instead.

And that forces us to go to CHALK FARM and then to CAMDEN TOWN, which it turns out is a truly excellent start.

Chalk Farm gifts us [CFHM], then Camden Town offers [DNOTW], and suddenly there are only seven letters [GJQUVXY] left to collect.

We can ignore U, because that comes for free when we collect Q, and G shouldn't be difficult to get either.

In which case the entire problem boils down to "What's the quickest way to grab J, Q, V, X and Y starting from Camden Town?"

I've knocked up a map.

• There are five X stations on the Underground (Brixton, Croxley, Oxford Circus, Uxbridge, Vauxhall), but only Oxford Circus is in the centre of town.
• There are three J stations on the Underground (St James's Park, St John's Wood and Willesden Junction), but the latter is too far out.

All my attempts at finding a best route pass through Oxford Circus, for the X, before heading on to either St John's Wood or St James's Park for the J.

It all comes down to how best to collect the Q, V and Y along the way.

• For Q, central London offers Queensway and four Something Squares.
• For V, either Covent Garden or Victoria look most promising.
• Although there are several Ys, Piccadilly Circus is the most central.

And here's what I reckon is the quickest way to complete the A-Z challenge (unless you can do better).

First the Northern line, Bank branch, south. That's 20 letters done already.
BELSIZe PARKCHalk FarM → CamDen TOWN → EUston
Then onto the Victoria line, via an easy cross platform interchange at Euston.
→ Warren Street → OXford Circus
Then to the Bakerloo line, via another easy cross platform interchange.
→ PiccadillY Circus → CharinG Cross → Embankment
And finally to the District line to pick off the final J, V and Q.
→ Westminster → St James's Park → Victoria → Sloane SQuare

This journey ticks off all 26 letters of the alphabet in 13 stations via four trains. I think that's unbeatable.

And, having tried it, it took 27 minutes. If only it had been 26.

Update: No, Chris can do it quicker, in just 12 stations! (but on seven trains, so slower)

BELSIZe PARKCHalk FarM → CamDen TOWN → EUston → Warren Street → OXford Circus → Tottenham Court Road → Leicester SQuare → PiccadillY Circus → Green Park Victoria → St James's Park

I then noticed that five of the stations I'd passed through hadn't contributed anything. If you take out Chalk Farm, Camden Town, Euston, Warren Street and Embankment, the other eight stations still contain all the letters of the alphabet between them.

BELSIZe PARK →→ OXForD CircUs → PiccadillY Circus → CHariNG Cross →→ WesTMinster → St James's Park → Victoria → Sloane SQuare

So here's my challenge for you. What's the fewest number of tube stations required so that every letter of the alphabet appears at least once? The stations don't have to be adjacent, they can be anywhere on the network.

Eight is beatable. Can you do it in seven, or six, or even five?

Update: Ian's done it in six.

[BELSIZe PARK, FUlHaM BrOaDWaY, QueeNsway, RodinG Valley, VauXhall, Willesden JunCTion]

Update: That used 71 letters, but Ian's second attempt only needs 59.

[BELSIZe PARK, BOroUGH, OXForD Circus, QueeNsWaY, ST JaMes's Park, Vauxhall]

Update: Swapping Vauxhall for Oval cuts this to 55 letters.

[BELSIZe PARK, BOroUGH, OVal, OXForD Circus, QueeNsWaY, ST JaMes's Park]

Update: Two readers, the wub and zin92, have slimmed it down to 52 letters.

[BELSIZe PARK, CHalk FarM, OVal, QUeeNsWaY, ST John's WooD, UXbridGe]

We're fairly certain six stations and 52 letters is the fewest possible. Thanks!

(but it used to be possible in five)

<< click for Newer posts

click for Older Posts >>

click to return to the main page

...or read more in my monthly archives
Jan20  Feb20  Mar20  Apr20  May20
Jan19  Feb19  Mar19  Apr19  May19  Jun19  Jul19  Aug19  Sep19  Oct19  Nov19  Dec19
Jan18  Feb18  Mar18  Apr18  May18  Jun18  Jul18  Aug18  Sep18  Oct18  Nov18  Dec18
Jan17  Feb17  Mar17  Apr17  May17  Jun17  Jul17  Aug17  Sep17  Oct17  Nov17  Dec17
Jan16  Feb16  Mar16  Apr16  May16  Jun16  Jul16  Aug16  Sep16  Oct16  Nov16  Dec16
Jan15  Feb15  Mar15  Apr15  May15  Jun15  Jul15  Aug15  Sep15  Oct15  Nov15  Dec15
Jan14  Feb14  Mar14  Apr14  May14  Jun14  Jul14  Aug14  Sep14  Oct14  Nov14  Dec14
Jan13  Feb13  Mar13  Apr13  May13  Jun13  Jul13  Aug13  Sep13  Oct13  Nov13  Dec13
Jan12  Feb12  Mar12  Apr12  May12  Jun12  Jul12  Aug12  Sep12  Oct12  Nov12  Dec12
Jan11  Feb11  Mar11  Apr11  May11  Jun11  Jul11  Aug11  Sep11  Oct11  Nov11  Dec11
Jan10  Feb10  Mar10  Apr10  May10  Jun10  Jul10  Aug10  Sep10  Oct10  Nov10  Dec10 
Jan09  Feb09  Mar09  Apr09  May09  Jun09  Jul09  Aug09  Sep09  Oct09  Nov09  Dec09
Jan08  Feb08  Mar08  Apr08  May08  Jun08  Jul08  Aug08  Sep08  Oct08  Nov08  Dec08
Jan07  Feb07  Mar07  Apr07  May07  Jun07  Jul07  Aug07  Sep07  Oct07  Nov07  Dec07
Jan06  Feb06  Mar06  Apr06  May06  Jun06  Jul06  Aug06  Sep06  Oct06  Nov06  Dec06
Jan05  Feb05  Mar05  Apr05  May05  Jun05  Jul05  Aug05  Sep05  Oct05  Nov05  Dec05
Jan04  Feb04  Mar04  Apr04  May04  Jun04  Jul04  Aug04  Sep04  Oct04  Nov04  Dec04
Jan03  Feb03  Mar03  Apr03  May03  Jun03  Jul03  Aug03  Sep03  Oct03  Nov03  Dec03
 Jan02  Feb02  Mar02  Apr02  May02  Jun02  Jul02 Aug02  Sep02  Oct02  Nov02  Dec02 

eXTReMe Tracker
jack of diamonds
Life viewed from London E3

» email me
» follow me on twitter
» follow the blog on Twitter
» follow the blog on RSS

my flickr photostream