Problem ID: alone
One evening you're visiting your uncle, you find yourself exploring his dark
basement. In a hidden drawer along some football cards you discover some old
and almost unreadable hand written notes. The title says season 1989/1990.
You examine the papers closely and discover numerous messages. Liverpool before ManchesterUnited one message says.
You are stunned. You can't believe what you're reading. What could this mean? Could it really be that Liverpool placed before Manchester United in the top division some time in the past? You quickly decide to investigate by making a program to decipher these messages into a sorted table.
Input is a list of league placement constraints between teams in the English top football division.
Each line in the input represents such a constraint, and indicates that one team places either somewhere before or somewhere after another team in the league.
All team names are given as single words, (team names with spaces are concatenated with CamelCase). You can assume that the constraints are consistent; i.e. that that a team can't be placed both before and after another team. You can also assume that for a set of constraints, there only exist one possible solution.
Output a sorted list of the teams in ascending order with regards to how they placed in the league.
Number of teams in a league is always greater than 1 and less or equal to 20.
Liverpool BEFORE ManchesterUnited
Chelsea AFTER ManchesterUnited
Chelsea AFTER Liverpool
Liverpool
ManchesterUnited
Chelsea