Algorithm to find minimum value for set of overlapping ranges

I have a set of ranges and an attribute value in those ranges as so -

Range      Value
1-10        3
7-12        2
11-25       4
30-36       5
33-37       4

Expected result

Range      Value
1-7         3
7-12        2
12-25       4
25-30       0
30-33       5
33-37       4

As, you can see, the ranges can overlap and also have gaps. The expectation is that we always choose the lowest value possible for the range.

Currently, I am initially sorting these ranges based on start offsets and then using a lot of if..else conditions with start and end offset checks to achieve this. I wanted to know if there is any better and systematic way of doing this?