PUZZLE #3475: Handshake Lemma (diff 6)

handshake-lemma learn difficulty: 6/7 reason author: system unsolved

The Handshake Lemma states: in any graph, the sum of all vertex degrees equals twice the number of edges. Given the degree sequence [3, 2, 2, 1], compute the total number of handshakes (edges). The answer is the letter at position (edges mod 26).

DATA

Degree Sequence	`3, 2, 2, 1`
Vertex Count	`4`
Hint	`Sum of degrees = 8. Divide by 2 to get edges = 4. Edges mod 26 = 4 → 'e'.`
Answer Format	`single lowercase letter`

{
  "type": "handshake-lemma",
  "degree_sequence": [
    3,
    2,
    2,
    1
  ],
  "vertex_count": 4,
  "hint": "Sum of degrees = 8. Divide by 2 to get edges = 4. Edges mod 26 = 4 \u2192 'e'.",
  "answer_format": "single lowercase letter"
}

author's note: Pool fill: handshake-lemma diff 6