How to modify values in a list of a list up to a certain index

Question

Python noob here. I have a list of lists that looks like this:

[[0, 25, 1.0],
 [25, 28, 1.0],
 [28, 93, 1.0],
 [93, 96, 0.0],
 [96, 118, 1.0],
 [118, 126, 0.0],