Google is known not only for its success, but also for the complexity of the questions that its employers ask during the interview. It can be held in a cafe or by video call, but questions will make even the most intelligent people nervous. Below is one of the simplest questions asked at the interview, which requires only logic.
Puzzle with billiard balls
You have 8 billiard balls, one of which is slightly heavier than the other seven. How many minimum weights do weights on weights without weights to find that ball?
It would seem difficult to give the right answer right away. But the problem is not such an impossible solution.
Answer: you can find the necessary billiard ball for at least two weighings.
Detailed solution
To understand which of the balls is the heaviest, you need to divide them into three parts. In two of them there will be 3 pieces of balls, and in the last - 2 balls. We do the weighing of the first two parts with the same number of balls. If any of them weighs more than the second, then we weigh any pair of billiard balls from it. Thus, either one of the two balls will turn out to be the one we are looking for, or it will not be weighted if the studied pair has the same weight. If the parts are equal, then the ball we need is in the third part.