🌳 When Stuck Decision Tree

Follow this systematic decision tree when you encounter difficult problems. Don’t waste time spinning your wheels - use this structured approach to find a solution or move on efficiently.

🎯 Initial Assessment (30 seconds)

First, Ask Yourself:

  • How long have I been on this problem? (If > 5 minutes, consider moving on)
  • Am I making progress? (If no progress, try different approach)
  • Do I understand what’s being asked? (If not, re-read carefully)
  • Is this problem worth my time? (Consider expected value)
  • What’s my confidence level? (Low confidence = try different approach)

Quick Time Check:

  • Problems 1-10: Don’t spend more than 3 minutes
  • Problems 11-15: Don’t spend more than 5 minutes
  • Problems 16-20: Don’t spend more than 7 minutes
  • Problems 21-25: Don’t spend more than 10 minutes

🔄 Tactic Switching (1-2 minutes)

If Current Approach Isn’t Working:

  • Switch from algebra to geometry: Try coordinate geometry or visual approach
  • Switch from geometry to algebra: Try setting up equations
  • Switch from direct to indirect: Try complement counting or working backwards
  • Switch from general to specific: Try plugging in specific values
  • Switch from complex to simple: Try a simpler approach

Tactic Switching Examples:

  • Algebra problem: Try backsolving with answer choices
  • Geometry problem: Try coordinate geometry
  • Counting problem: Try complement counting
  • Number theory problem: Try modular arithmetic
  • Function problem: Try graphing or specific values

🎯 Complement Approaches (1-2 minutes)

When Direct Approach is Hard:

  • Count what you don’t want: Use complement counting
  • Work backwards: Start from the answer and work back
  • Use “at least” logic: Count “none” and subtract
  • Use “at most” logic: Count “more than” and subtract
  • Use probability complements: $P(A) = 1 - P(A^c)$

Complement Examples:

  • “At least one”: Count “none” and subtract from total
  • “At most one”: Count “more than one” and subtract from total
  • “Not all”: Count “all” and subtract from total
  • “Some but not all”: Count “all” and “none”, then subtract

🔍 Symmetry and Patterns (1-2 minutes)

Look for Symmetry:

  • Geometric symmetry: Use symmetric properties
  • Algebraic symmetry: Use symmetric substitutions
  • Combinatorial symmetry: Use symmetric counting
  • Numerical symmetry: Use symmetric patterns
  • Functional symmetry: Use even/odd properties

Pattern Recognition:

  • Look for cycles: Find repeating patterns
  • Look for sequences: Find arithmetic or geometric patterns
  • Look for formulas: Find known formulas that apply
  • Look for identities: Find trigonometric or algebraic identities
  • Look for special cases: Find cases that are easier to handle

🔄 Backsolving and Answer Choice Exploitation (1-2 minutes)

When Direct Solving is Hard:

  • Try answer choices: Plug in each choice
  • Start with middle choice: Often C or D
  • Use binary search: Go higher or lower based on result
  • Eliminate obviously wrong: Cross out impossible answers
  • Use answer choice patterns: Look for patterns in choices

Backsolving Process:

  1. Start with middle choice: Try C or D
  2. Test the value: Substitute into problem
  3. Compare result: Does it match what’s asked?
  4. Adjust direction: Go higher or lower based on result
  5. Narrow down: Use binary search approach

🎯 Coordinate and Visual Approaches (1-2 minutes)

When Abstract Approach is Hard:

  • Draw a diagram: Visualize the problem
  • Use coordinate geometry: Place in coordinate system
  • Use graphing: Plot functions or relationships
  • Use visualization: Create mental or physical models
  • Use symmetry: Apply symmetric properties

Visual Approach Examples:

  • Geometry problem: Draw accurate diagram
  • Function problem: Graph the function
  • Counting problem: Use Venn diagrams or tree diagrams
  • Algebra problem: Graph both sides of equation
  • Number theory problem: Use number line or grid

⚡ Quick Approximation and Estimation (1 minute)

When Exact Solution is Hard:

  • Use estimation: Approximate the answer
  • Use bounds: Find upper and lower bounds
  • Use order of magnitude: Estimate the scale
  • Use special values: Try $x = 0, 1, -1$
  • Use extreme cases: Test boundary values

Approximation Examples:

  • Large numbers: Use scientific notation
  • Complex expressions: Use approximation formulas
  • Geometric problems: Use approximate values
  • Counting problems: Use approximation techniques
  • Probability problems: Use approximation methods

🚨 Emergency Protocols (30 seconds)

When All Else Fails:

  • Make an educated guess: Use elimination and intuition
  • Use expected value: Apply guessing strategy
  • Move on: Don’t waste more time
  • Mark for later: Come back if time permits
  • Stay calm: Don’t let one problem ruin your contest

Guessing Strategy:

  • Eliminate obviously wrong: Cross out impossible answers
  • Use partial information: Apply what you know
  • Use symmetry: Choose symmetric answer if applicable
  • Use intuition: Go with your gut feeling
  • Use expected value: Apply mathematical guessing strategy

📊 Decision Tree Summary

Time-Based Decisions:

  • 0-2 minutes: Try different approach
  • 2-5 minutes: Try complement or symmetry
  • 5-10 minutes: Try backsolving or approximation
  • 10+ minutes: Make educated guess or move on

Problem-Based Decisions:

  • Easy problems (1-10): Don’t get stuck, move on quickly
  • Medium problems (11-15): Try 2-3 different approaches
  • Hard problems (16-20): Try 1-2 approaches, then guess
  • Very hard problems (21-25): Try 1 approach, then guess

Confidence-Based Decisions:

  • High confidence: Continue with current approach
  • Medium confidence: Try different approach
  • Low confidence: Try complement or backsolving
  • No confidence: Make educated guess or move on

⚡ Quick Reference

When Stuck Checklist:

  • How long? (If > time limit, move on)
  • Making progress? (If no, try different approach)
  • Understand problem? (If not, re-read)
  • Worth my time? (Consider expected value)
  • Confidence level? (Low = try different approach)

Recovery Actions:

  • Switch tactics: Try different approach
  • Use complement: Count what you don’t want
  • Look for symmetry: Use symmetric properties
  • Try backsolving: Use answer choices
  • Use approximation: Estimate the answer
  • Make educated guess: Use elimination and intuition

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