Find the year with the most number of people alive in Python

Question

Given a list of people with their birth and end years (all between 1900 and 2000), find the year with the most number of people alive.

Here

Answer 1

How about this one:

def max_pop(pop):
    p = 0; max = (0,0)
    for y,i in sorted(chain.from_iterable([((b,1), (d+1,-1)) for b,d in pop])):
        p += i
        if p > max[1]: max=(y,p)
    return max

It's not affected by the year span but is nlogn in the |pop| (unless you'd roll out a radix sort which would be ~ 10n for a thousand year span and should be faster for |pop|>1000 ). Can't have both. A very general solution would have to scan first and decide which algo to use based on measured year span and |pop|.