Programming Praxis

We have today an exercise inspired by those “programming challenge” websites where you upload code and an automated judge tells if you pass or fail and how your time compares to other programmers. I haven’t seen this particular problem at one of those sites, but it feels like something they would do; this would also make a good interview question:

You are given a list of people’s lifespans with birth and death years; for instance, a person lived from 1924 to 1991. Some people have only a birth year because they are still living. You are to find the year in which the most people of a set of people were alive.

Input: A number n on a line by itself indicating the number of input cases, followed by n sets of lines containing a number m indicatingthe number of people in this particular input case, followed by m lines indicating birth and, possibly, death years.

Output: For each input case, the year (or years) in which the most people were alive.

Example: For the input:

2
3
1910 1948
1948 2011
1927 1995
3
1910 1948
1927 1995
1945

You should produce the following output:

1948
1945 1946 1947 1948

Your task is to write the indicated program. When you are finished, you are welcome to read or run a suggested solution, or to post your own solution or discuss the exercise in the comments below.

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