nchn27's blog

Forgotten Problem
By nchn27, history, 4 years ago, In English

We have an array of (10^5?) integers and we have to count the number of subsequences of length 3 that are also arithmetic progressions. I believe they also have to be in the right order.

I googled so hard but I forget the problem name and solution. The problem should be on CodeForces. I vaguely remember a cool solution involving hashing?

Can anyone please help me find the problem / solution

  • Vote: I like it
  • +11
  • Vote: I do not like it

»
4 years ago, # |
  Vote: I like it +5 Vote: I do not like it

This?

→ Reply
»
4 years ago, # |
  Vote: I like it 0 Vote: I do not like it

I guess you're talking about this one (even though it's for a permutation).

452F - Permutation

→ Reply