Balancing Bank Accounts
Time Limit: 2 Seconds
Memory Limit: 65536 KB
Once upon a time there was a large team coming home from the ACM World Finals.
The fifteen travellers were confronted with a big problem:
In the previous weeks, there had been many money transactions between them: Sometimes
somebody paid the entrance fees of a theme park for the others, somebody else
paid the hotel room, another one the rental car, and so on.
So now the big calculation started. Some people had paid more than others,
thus the individual bank accounts had to be balanced again. "Who has to
pay whom how much?", that was the question.
As such a calculation is a lot of work, we need a program now that will solve
this problem next year.
The input will contain one or more test cases.
Each test case starts with a line containing two integers: the number of travellers
n (2 <= n <= 20) and the number of transactions t (1 <= t <= 1000).
On the next n lines the names of the travellers are given, one per line. The
names only consist of alphabetic characters and contain no whitespace. On the
following t lines, the transactions are given in the format name1 name2 amount
where name1 is the person who gave amount dollars to name2. The amount will
always be a non-negative integer less than 10000.
Input will be terminated by two values of 0 for n and t.
For each test case, first print a line saying "Case #i" where i is
the number of the test case.
Then, on the following lines, print a list of transactions that reverses the
transactions given in the input, i.e. balances the accounts again. Use the same
format as in the input. Print a blank line after each test case, even after
the last one.
- Your solution must consist of at most n-1 transactions.
- Amounts may not be negative, i.e. never output "A B -20", output
"B A 20" instead.
If there is more than one solution satisfying these restrictions, anyone is
Donald Dagobert 15
John Mary 100
John Cindy 200
Cindy Mary 40
Cindy Arnold 150
Dagobert Donald 15
Mary John 140
Cindy John 10
Arnold John 150
Source: University of Ulm Local Contest 1998