MathCastle
Graph TheoryEasyGraph Coloring

Graph Coloring · Easy problem

Six meeting rooms sit around a hexagonal corridor, numbered 11 through 66 in order, so room ii shares a wall with room i+1i+1 (and room 66 with room 11). A shortcut corridor also directly connects room 11 to room 44. Any two rooms joined by a wall or the shortcut must be painted different colors. What is the fewest colors needed?