# Merge working time periods

You have an array of working time period pairs (from, till) received from user input and written according 24-hour clock format convention. You have to merge these periods if the intersect each other.

For example, if you have (10, 12), (11, 13), (12, 14) you should merge them into (10,14). Also (23, 0) and (0, 1) should be merged into (23, 1).

UPDATE:

@dmckee Let assume that the set of pairs like (10:00, 12:00) is the valid input.

@dude We don't consider Sundays and holidays so all merges should be performed for the common twenty-four hours range.

@steven-rumbalski The result of (0,8), (8,16), (16,0) may be any (x,x) pair, for example, (00:00,00:00).

Example 1

Input

(09:00,12:00),(11:00,13:00),(17:00,19:00)


Output

(09:00,13:00),(17:00,19:00)


Example 2

Input

(00:00,08:00),(08:00,16:00),(16:00,00:00)


Output

(00:00)

• Is (10,12) a valid input, or should it be (10:00, 12:00) or something similar? Likewise, what is the correct format for the output? Also each challenge should specify what the metric is (i.e. we don't only do [code-golf] or even default to it). – dmckee Jan 11 '13 at 15:20
• Because one work shift can spill over from one day into the next [as (23,0)+(0,1) =(23,1) appears to show], shouldn't we be keeping track of the days in the workweek also? If Sunday is not a work day, it would seem that (23,1), starting Sunday Evening and going to 1 am Monday, would not count. However, from Monday to Tuesday, it would be counted. – DavidC Jan 11 '13 at 16:32
• What should the result of (0,8), (8,16), (16,0) be? – Steven Rumbalski Jan 11 '13 at 16:41
• In the future, maybe post your spec to the sandbox on meta first to get feedback before you post. This could have been a great question with a little more work. – Tim Seguine Feb 24 '14 at 22:20

# Python (198 chars)

r=[]
p=r.append
l=r+sorted(a<b and (a,b)or p((0,b))or(a,24)for a,b in input())
r[:]=[]
a,b=l
for c,d in l[1:]:
if c>b:p((a,b));a,b=c,d
elif b<d:b=d
if b>23:b=a and r.pop(0)
p((a,b))
print r


Example:

> python merge.py
(10, 12), (11, 13), (12, 14)
[(10, 14)]
> python merge.py
(23,0),(0,1)
[(23, 1)]
> python merge.py
(0,8), (8,16), (16,0)
[(0, 0)]