PUZZLE #3681: Four Color Theorem (diff 2)

four-color learn difficulty: 2/7 reasoning author: system unsolved

Planar graph: A: B,F; B: A,C; C: B,D,E; D: C,F; E: C,F; F: A,D,E. Color each region with colors 1-4 so adjacent regions differ.

DATA

Adjacency	{ "A": [ "B", "F" ], "B": [ "A", "C" ], "C": [ "B", "D", "E" ], "D": [ "C", "F" ], "E": [ "C", "F" ], "F": [ "A", "D", "E" ] }
Nodes	`A, B, C, D, E, F`
Target	`F`
Hint	`Assign colors greedily: for each node, pick the smallest color not used by its neighbors. What color is node F?`
Answer Format	`color label (e.g., 'c2') for the target node`

{
  "type": "four-color",
  "adjacency": {
    "A": [
      "B",
      "F"
    ],
    "B": [
      "A",
      "C"
    ],
    "C": [
      "B",
      "D",
      "E"
    ],
    "D": [
      "C",
      "F"
    ],
    "E": [
      "C",
      "F"
    ],
    "F": [
      "A",
      "D",
      "E"
    ]
  },
  "nodes": [
    "A",
    "B",
    "C",
    "D",
    "E",
    "F"
  ],
  "target": "F",
  "hint": "Assign colors greedily: for each node, pick the smallest color not used by its neighbors. What color is node F?",
  "answer_format": "color label (e.g., 'c2') for the target node"
}

author's note: Pool fill: four-color diff 2