Convert a color rule into an algorithm

Table 1 defines the result of combining two different colors. Each input is Red, Yellow, or Blue. Input order does not change the result.

Table 1: Results defined by the color-combination rule.

First color	Second color	Result
Red	Yellow	Orange
Yellow	Blue	Green
Blue	Red	Purple

The algorithm receives color_1 and color_2. Capitalization has already been normalized. A pair is valid when it contains two different listed colors and matches one table row in either order. For a repeated color or any other word, output Invalid combination.

Write pseudocode for the rule. Then give the outputs for (Yellow, Red), (Blue, Yellow), (Red, Red), and (Green, Blue).

TipHint

Each table row represents two possible input orders.