Union of multiple ranges

Question

I have these ranges:

7,10
11,13
11,15
14,20
23,39

I need to perform a union of the overlapping ranges to give ranges that are not overlappi

Answer 1

Let's say, (7, 10) and (11, 13) result into (7, 13):

a = [(7, 10), (11, 13), (11, 15), (14, 20), (23, 39)]
b = []
for begin,end in sorted(a):
    if b and b[-1][1] >= begin - 1:
        b[-1] = (b[-1][0], end)
    else:
        b.append((begin, end))

b is now

[(7, 20), (23, 39)]

EDIT:

As @CentAu correctly notices, [(2,4), (1,6)] would return (1,4) instead of (1,6). Here is the new version with correct handling of this case:

a = [(7, 10), (11, 13), (11, 15), (14, 20), (23, 39)]
b = []
for begin,end in sorted(a):
    if b and b[-1][1] >= begin - 1:
        b[-1][1] = max(b[-1][1], end)
    else:
        b.append([begin, end])