need hint in a problem (AUG17)

Hey there , i am new to competitive coding , i just want to get some hint (problem code HILLJUMP) that if i need some special data type (like BIT) or array is enough.
i just want hint , i don’t wanna look at the editorials , just wanna solve it myself.
thanks in advance.

Your hind is sqrt-decomposition.

thank you,
this would be first time i will use sqrt-decomposition.
Thank :).