ape-alphacode-pass-1-explicit

name	ape - Alphacode Pass 1 Explicit
description	First pass at competitive programming — explicit problem decomposition, constraint identification, and straightforward implementation.
output	{"format":"prose"}

Alphacode Pass 1 Explicit

Input: $ARGUMENTS

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Overview

Pass 1 is about getting the problem RIGHT before getting clever. Explicitly decompose the problem, identify every constraint, enumerate edge cases, and implement the most straightforward correct solution. Optimization comes later.

Steps

Step 1: Parse the Problem Statement

1. Read the entire problem statement twice
2. Extract:
   • Input format: exact specification
   • Output format: exact specification
   • Constraints: all numerical bounds (N, M, time, memory)
   • Guarantees: what the problem promises about input
3. Restate the problem in your own words
4. What is the problem ACTUALLY asking? (often different from how it's worded)

Step 2: Classify the Problem Type

1. Core algorithmic category:
   • Graph / DP / Greedy / Math / String / Data structure / Search / Ad hoc
2. Note if combination of types
3. Identify the key insight being tested

Step 3: Work Through Examples

1. Trace through EVERY provided example by hand
2. Verify your understanding produces expected output
3. If mismatch → problem interpretation is wrong, go back to Step 1
4. Construct 2-3 additional small examples
5. Look for patterns

Step 4: Identify Edge Cases

1. Minimum input (N=1, empty, single element)
2. Maximum input (upper constraint bounds)
3. All-same input
4. Sorted / reverse sorted
5. Boundary values (0, -1, MAX_INT)
6. Problem-specific (disconnected graph, self-loops, duplicates)
7. Write expected output for each

Step 5: Design Algorithm

1. Start with brute force
2. Calculate complexity: O(?) time, O(?) space
3. Does brute force pass? If yes → implement it. Simplicity > cleverness in Pass 1.
4. If no → identify bottleneck, determine needed optimization
5. State what each step does, why it's correct, its complexity

Step 6: Implement

1. Clean, straightforward code
2. Descriptive variable names
3. Handle input parsing carefully (off-by-one = #1 bug)
4. Comment each major section

Step 7: Test

1. Run against ALL provided examples
2. Run against edge cases from Step 4
3. If failure → don't patch, understand WHY, fix root cause
4. All pass → proceed to /api (Pass 2) if optimization needed

PASS 1 RESULT:
Problem type: [classification]
Algorithm: [description]
Complexity: O([time]) time, O([space]) space
Passes constraints: [yes/no]
Edge cases: [N of N passed]
Status: [correct / needs optimization / stuck]

When to Use

• First attempt at any competitive programming problem
• When you need a correct baseline before optimizing

Verification

• Problem restated in own words
• All constraints extracted
• Every example traced by hand
• Edge cases enumerated and tested
• Correctness argued (not just tested)
• Complexity checked against limits