PUZZLE #4285: Eulerian Path Cipher (diff 1)

eulerian-path learn difficulty: 1/7 reason author: system unsolved

A graph with 4 labeled vertices and 3 edges. Find an Eulerian path visiting each edge exactly once. Vertex labels along the path spell the answer.

DATA

Vertices	`l, e, a, f`
Edges	`{'u': 'l', 'v': 'e', 'id': 0}, {'u': 'e', 'v': 'a', 'id': 1}, {'u': 'a', 'v': 'f', 'id': 2}`
Adjacency	{ "l": [ "e" ], "e": [ "l", "a" ], "a": [ "e", "f" ], "f": [ "a" ] }
Hint	`Graph with 4 vertices. An Eulerian path uses every edge exactly once. Trace the path — vertex labels in order spell the answer. 0 or 2 vertices have odd degree, so an Eulerian path exists.`
Answer Format	`lowercase word, no spaces (4-6 letters)`

{
  "type": "eulerian-path",
  "vertices": [
    "l",
    "e",
    "a",
    "f"
  ],
  "edges": [
    {
      "u": "l",
      "v": "e",
      "id": 0
    },
    {
      "u": "e",
      "v": "a",
      "id": 1
    },
    {
      "u": "a",
      "v": "f",
      "id": 2
    }
  ],
  "adjacency": {
    "l": [
      "e"
    ],
    "e": [
      "l",
      "a"
    ],
    "a": [
      "e",
      "f"
    ],
    "f": [
      "a"
    ]
  },
  "note": "An Eulerian path visits each edge exactly once. Vertex labels in path order spell the answer.",
  "hint": "Graph with 4 vertices. An Eulerian path uses every edge exactly once. Trace the path \u2014 vertex labels in order spell the answer. 0 or 2 vertices have odd degree, so an Eulerian path exists.",
  "answer_format": "lowercase word, no spaces (4-6 letters)"
}

author's note: Pool fill: eulerian-path diff 1