Firstly it's comfortable to use recursive scheme of DP.
Secondly : I've STAK_OVERFLOW when tried to take DP form 1 to sqrt(n), but AC when sqrt(n) downto 1. I don't know what's the differnce but result depend of it

I think, you don't need DP in this problem. It can be solved with simple O(n^1.5) algorithm.

would you please further explain the O(n^1.5) and non-DP approach?

Thanks,

i don't know why it is not dp, but i think he was mentioned BFS