MathDB
Problems
Contests
National and Regional Contests
India Contests
India EGMO TST
India EGMO 2021 TST
1
1
Part of
India EGMO 2021 TST
Problems
(1)
Mad scientist writes numbers
Source: India EGMO 2021 TST P1
11/18/2021
Mad scientist Kyouma writes
N
N
N
positive integers on a board. Each second, he chooses two numbers
x
,
y
x, y
x
,
y
written on the board with
x
>
y
x > y
x
>
y
, and writes the number
x
2
ā
y
2
x^2-y^2
x
2
ā
y
2
on the board. After some time, he sends the list of all the numbers on the board to Christina. She notices that all the numbers from 1 to 1000 are present on the list. Aid Christina in finding the minimum possible value of N.
discrete system
invariant