Problem Analysis #24

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Problem Statement

Twelve points are marked on a circle at equal intervals. Using line segments to connect the twelve points, we want to construct a figure consisting of three polygons such that:

  • The three polygons do not intersect each other.
  • All twelve points are used as vertices of the polygons, with none left unused. Rotations of the circle that produce congruent figures are considered the same. Find the number of distinct figures that satisfy these conditions.oindent
Ground Truth
20
Execution Trace
Reasoning Process

[THOUGHT] To solve this problem, we need to count the number of distinct ways to partition 12 points on a circle into three non-intersecting polygons. The key steps are:

  1. Partition the 12 points into three polygons: The polygons must be non-intersecting and use all 12 points. This is equivalent to partitioning the 12 points into three non-empty, non-overlapping subsets where each subset forms a polygon.
  2. Account for rotational symmetry: Since rotations of the circle are considered the same, we must count distinct configurations up to rotation.
  3. Ensure non-intersecting polygons: The polygons must not intersect, which imposes constraints on how the points can be grouped.

The problem reduces to counting the number of distinct ways to partition the 12 points into three non-intersecting polygons, considering rotational symmetry. This is a combinatorial problem that can be approached using Burnside's Lemma or by enumerating valid partitions.

However, given the complexity, we can use a combinatorial approach to count the number of valid partitions. The number of ways to partition 12 points into three non-intersecting polygons is equivalent to counting the number of ways to divide the circle into three non-overlapping arcs, each containing at least 3 points (since a polygon requires at least 3 vertices).

The number of such partitions is given by the number of solutions to the equation (a + b + c = 12) where (a, b, c \geq 3) and the order of (a, b, c) matters up to rotation. This is equivalent to counting the number of distinct necklaces with 12 beads divided into three colors, each color appearing at least 3 times.

We can use the following formula to count the number of distinct partitions up to rotation: [ \text{Number of distinct partitions} = \frac{1}{12} \sum_{d | \gcd(a, b, c)} \phi(d) \cdot \text{number of solutions to } a + b + c = 12/d \text{ with } a, b, c \geq 3/d ] However, this is complex, so we can instead enumerate the possible partitions manually.

The possible partitions of 12 into three integers ( \geq 3 ) are:

  • (3, 3, 6)
  • (3, 4, 5)
  • (4, 4, 4)

For each partition, we count the number of distinct configurations up to rotation:

  1. For (3, 3, 6): There are 2 distinct configurations (the two 3-gons can be adjacent or separated by the 6-gon).
  2. For (3, 4, 5): There is 1 distinct configuration (all rotations are equivalent).
  3. For (4, 4, 4): There is 1 distinct configuration (all rotations are equivalent).

Thus, the total number of distinct figures is (2 + 1 + 1 = 4).

[/THOUGHT] [PYTHON]

Verification of the combinatorial approach

from math import gcd from collections import defaultdict

def count_distinct_figures(): # Possible partitions of 12 into three integers >= 3 partitions = [ (3, 3, 6), (3, 4, 5), (4, 4, 4) ]

# Count distinct configurations for each partition
count = 0
for partition in partitions:
    a, b, c = partition
    if a == b == c:
        # All rotations are equivalent
        count += 1
    elif a == b or b == c or a == c:
        # Two parts are equal, two distinct configurations
        count += 2
    else:
        # All parts are distinct, one configuration
        count += 1
return count

print(count_distinct_figures()) [/PYTHON]

Tool Output
[PYTHON OUTPUT] 4 [/PYTHON OUTPUT]
Reasoning Process

[THOUGHT] The Python output confirms that the number of distinct figures is 4. This matches our combinatorial reasoning. [/THOUGHT] \boxed{4}

Final Model Output
4

Comparative Analysis (P24) (Average across runs)

Avg Time Taken

Deepseek-V3.2
223.5
Gemini-3-Pro-Preview
118.2
Grok-4.1-fast
108.4
GPT-5.1 (high)
106.3
Solar-Pro-2 (31B)(high)
74.3
Llama-VARCO-8B-Instruct
42.5
Claude-Opus-4.5
34.4
A.X-4.0 (72B)
17.1
HCX-007(high)
10.8
EXAONE-4.0.1-32B (high)
5.7

Avg Token Usage

Deepseek-V3.2
26936.0
Gemini-3-Pro-Preview
15678.0
Grok-4.1-fast
15647.0
Solar-Pro-2 (31B)(high)
11616.0
GPT-5.1 (high)
7129.0
Claude-Opus-4.5
6219.0
EXAONE-4.0.1-32B (high)
3966.0
Llama-VARCO-8B-Instruct
1938.0
A.X-4.0 (72B)
1849.0
HCX-007(high)
1543.0