I'm confused on what you're suggesting. The code is for range update point query. Each query goes down the entire tree. The query is a sum query. Have you tested this? Does it not work? I'm on my phone but it looks right to me.

What I'm suggesting is a "build" function that works for range update/maximum query, since there isn't one in the code. You're right, for point query this wouldn't work. What I wrote should go in the section below, "Adding on segments, querying for maximum"

Changed commit message and title to better reflect the proposed change.

Hi, thanks for the pull request! Have you tested this implementation against any existing problem?

Hello and happy new year!
I have implemented the algorithm along with unit tests here:
https://github.com/akoutian/algs/tree/master/src/algs/segtree

The unit tests check for correctness against various inputs.

Cheers!