In Codeforces Round 433 Div 2, I have seen a solution of problem E.

Since, the value of n was 200000. So it was not possible to solve the problem by declaring a n*n(200000*200000) array.

But, In that solution a solver has used a vector efficiently instead of two dimensional array. I have tried but couldn't got this.

Can anyone please help me on this?

Thanks in advance.

Which solution were you looking at?

You have only one square per row and only one square per column, for a total of

Nsquares, so you only need to storeNvalues, you don't need 2D.