Four people are in a bar.

Ben owes Glen a drink. Glen owes Rhen two drinks. Rhen owes Sven three drinks. Sven owes Ben four drinks.

To settle up, what is the minimum number of drinks that need to be bought by who for whom?

(In reply to

answer by K Sengupta)

Let the respective total number of drinks that the remaining three persons (except the designated individual) oews to Ben, Glen, Rhen and Sven be b, g, r and s.

(For example, b denotes the total number of drinks that the three persons owe to Ben)

Then, by the problem, we have:

b = -1 + 4 = 3

g = -2 + 1 = -1

r = -3 + 2 = -1

s = -4 + 3 = -1

Thus, Ben needs a total of three drinks while each of Sven, Rhen and Glen owes one drink.

Accordingly, the simplest avenue to clear off the respective debts is for each of the three persons, that is - Sven, Rhen and Glen to buy Ben one drink.