So I have been trying to read on some articles in attempt to solve the recent CodeChef Long. I came across this article but I cannot understand it. It asks us to build array $$$t[]$$$ using $$$d[]$$$ , and then tells us to find $$$d[]$$$ using maximum of a prefix of $$$t[]$$$ using segment tree. If we are already building $$$t[]$$$ using $$$d[]$$$ , why do we need to find $$$d[]$$$ again.

Thanks.