## Sunday, October 19, 2014

### A Classic Puzzle

This problem can be solved by pre-school children in 5-10 minutes, by programmers - in 1 hour, by people with higher
education ... well, check it yourself! :)

8809=6
7111=0
2172=0
6666=4
1111=0
3213=0
7662=2
9313=1
0000=4
2222=0
3333=0
5555=0
8193=3
8096=5
7777=0
9999=4
7756=1
6855=3
9881=5
5531=0
2581=?

1. Nice! (About 30 seconds, I think. But it could easily have been much longer, and in any case I'm not more than 60% confident I haven't seen it before.)

1. (Clarification: "it could easily have taken me much longer, in a hypothetical slightly-different world", not "it could easily be the case that it actually did take me much longer, here in the real world".)

2. 30 seconds! 30 seconds!! OK, I am in awe. Even the smallest children can't do this in 30 seconds. It took me about 10 minutes to come up with the really bad unsatisfying answer, and I didn't see the answer from the Book until somebody told me.

2. Well, as I say it's possible I've seen it before. Regardless, I think I mostly got lucky. I've definitely been very slow about problems of this kind on other occasions.

3. 30 secs and im a programmer