IMO 1979 LL HUN39
A desert expedition camps at the border of the desert, and
IMO 1979 LL HUN39
Origin: HUN
Problem
A desert expedition camps at the border of the desert, and has to provide one liter of drinking water for another member of the expedition, residing on the distance of n days of walking from the camp, under the following conditions: (i) Each member of the expedition can pick up at most 3 liters of water. (ii) Each member must drink one liter of water every day spent in the desert. (iii) All the members must return to the camp. How much water do they need (at least) in order to do that?