MathDB
Luffy always lures magic things

Source: Rioplatense L3 2023 #4

December 6, 2023
combinatorics

Problem Statement

Luffy is playing with some magic boxes and a machine. Each box has a value(number) inside. Opening a box, Luffy sees the value, adds the value to his score(if the box value is negative, Luffy loses points) and destroys the box. Putting a box of value XX in the machine, this box vanishes and it is replaced by two new boxes of values X+1X+1 and X1X-1(it's not known which one has the respective value, but he can identify the new boxes). At the beginning, Luffy has 00 points and has a box whose value is known(it is zero). a) Prove that Luffy can reach at least 10001000 points b) Is it possible that Luffy reaches at least 10000001000000 points, without have less than 42-42 points in any moment?