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Colorful Integers

Source: Indonesian National Mathematical Olympiad, Problem 5

August 29, 2024
combinatoricsIntegersnumber theoryIndonesiaIndonesia MOInamo

Problem Statement

Each integer is colored with exactly one of the following colors: red, blue, or orange, and all three colors are used in the coloring. The coloring also satisfies the following properties:
1. The sum of a red number and an orange number results in a blue-colored number, 2. The sum of an orange and blue number results in an orange-colored number; 3. The sum of a blue number and a red number results in a red-colored number.
(a) Prove that 00 and 11 must have distinct colors. (b) Determine all possible colorings of the integers which also satisfy the properties stated above.