I sometimes question all purpose

[r6mez]

Added some blackboxes

• a coordinate-compression helper
• a positive-divisor counting for large numbers (< 1e18)
• add a dynamic double-hash segment tree for substring and palindrome queries

My feelings about all this are still unmoved; I just want to go through it.

[AnonMiraj]

number of divisors and cords comp is kinda useless
I mean you can literally just do this

map<int, int> m; for (int x : a) m[x] = 0;
int idx = 0; for (auto& p : m) p.second = idx++;

but I longer care.