IOM 2017, Блиц — Задача 50

OLYMPIAD OF METROPOLISES. Moscow, September 4 · 4 септември 2017 г.

Условие

A physicist, chemist, biologist and a mathematician are out walking. They come to an old bridge. The bridge is weak and can carry only two of them at the same time. Since they are late to the university and the light is fading they must cross in the minimum time possible and must carry a flashlight on every crossing. They only have one flashlight and it can only be delivered by hand (e.g. after the first two cross, one has to return with the flashlight). Because of their different age, each one crosses the bridge in a different speed. The physicist can cross in 1 minute, the chemist in 2 minutes, the biologist in 5 minutes and the mathematician in 10 minutes.

What is the minimum possible time for all of them to cross the bridge, if they perform optimally?

Отговори

Решение

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Оригинал в Архива: blitz.pdf · официални решения: answers-blitz.pdf