Problem Analysis #6

Solar-Open-100B · Run 1

58.04s
10,843 toks
Problem Statement

Let VV be the set {1,2,,11}\{1, 2, \dots, 11\}. Consider a sequence (v0,v1,,vn)(v_0, v_1, \dots, v_n) of elements from VV of length nn that forms a closed loop where the last element equals the first (vn=v0v_n = v_0). The sequence must satisfy the condition that any two elements are distinct if they are adjacent or separated by exactly one position. This restriction also applies to the boundary, specifically requiring that v1vn1v_1 \neq v_{n-1}. \nLet knk_n denote the total number of such sequences of length nn.\nDetermine the exact integer value of k10k_{10}.

Ground Truth
3486906720
Execution Trace
Reasoning Process

[THOUGHT] We need to count the number of proper colorings of a cycle of length L=n+1=11L=n+1=11 with 11 colors such that no two vertices at distance 1 or 2 share the same color.
This can be modeled as a walk on the state graph where a state is an ordered pair of distinct colors (a,b)(a,b).
From (a,b)(a,b) we may go to (b,c)(b,c) iff cac\neq a and cbc\neq b.
The number of valid sequences of length LL forming a closed loop equals the trace of the adjacency matrix MM of this state graph raised to the LL‑th power: kn=tr(ML)k_n = \operatorname{tr}(M^{L}).

We will:

  1. Enumerate all ordered pairs of distinct colors from {0,,10}\{0,\dots,10\} (11 colors).
  2. Build the 110×110110\times110 adjacency matrix MM where M[(a,b),(b,c)]=1M[(a,b),(b,c)]=1 iff ca,bc\neq a,b.
  3. Compute tr(M11)\operatorname{tr}(M^{11}).

[/THOUGHT] [PYTHON] import numpy as np

number of colors

C = 11

generate all ordered pairs (a,b) with a != b

pairs = [(a, b) for a in range(C) for b in range(C) if a != b] N = len(pairs) # 110

map pair to index

pair_to_idx = {pair: i for i, pair in enumerate(pairs)}

build adjacency matrix

M = np.zeros((N, N), dtype=int)

for i, (a, b) in enumerate(pairs): for c in range(C): if c != a and c != b: j = pair_to_idx[(b, c)] M[i, j] = 1

compute trace of M^L for L = 11

L = 11 M_L = np.linalg.matrix_power(M, L) trace = int(np.trace(M_L))

trace [/PYTHON]

Tool Output
[PYTHON OUTPUT] 31384473120 [/PYTHON OUTPUT]
Reasoning Process

[THOUGHT] The Python computation confirms that the number of valid sequences is 31384473120. [/THOUGHT] 31384473120\boxed{31384473120}

Final Model Output
31384473120

Comparative Analysis (P6) (Average across runs)

Avg Time Taken

Gemini-3-Pro-Preview
1028.1
EXAONE-4.0-32B
426.8
Kanana-2-30B-Thinking-2601
190.9
Kanana-2-30B-Thinking
104.4
Solar-Pro 2
86.8
Solar-Open-100B
69.3
K-EXAONE-236B-A23B
62.9
GLM-4.5-Air
48.9
GPT-5.2 (high)
34.5
HCX-007
32.3

Avg Token Usage

Kanana-2-30B-Thinking-2601
29992.7
Gemini-3-Pro-Preview
24197.7
Kanana-2-30B-Thinking
17532.3
Solar-Pro 2
16928.7
Solar-Open-100B
12645.0
K-EXAONE-236B-A23B
8254.7
GLM-4.5-Air
5984.0
HCX-007
5751.3
EXAONE-4.0-32B
5189.7
GPT-5.2 (high)
5091.7