I always can't figure out some questions clearly.

For example, this question: cf1953e

I can think of if there are two ones that can be zeroed directly to complete the task, and think of preprocessing which ones can be zeroed.

But my thinking is very chaotic. For example, when I first thought about line segment trees and thought about preprocessing, I found that it didn't work. Then I thought about binary bits again, and when I thought about the key, I couldn't think of preprocessing.

Seek help.