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Contest Strategy

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The Winning Mindset

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Understanding Contest Formats

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Codeforces Format

• 800-1200: Focus on solving A and B quickly
• 1200-1400: Solve A, B, C; attempt D
• 1400-1600: Solve A-D consistently; attempt E
• 1600+: Speed on A-C, deep thinking on D+

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ICPC Format

• Team of 3, 1 computer
• 5 hours, 10-13 problems
• Scoring: Most problems solved, then fewest penalty minutes
• No partial credit: Solution must pass all test cases

• Assign problems by specialty (graphs, DP, math, etc.)
• One person reads while another codes
• Easy problems first to build momentum
• Keep one person thinking about hard problems

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The First 10 Minutes

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Codeforces Routine

0:00 - Read Problem A
0:02 - Code and submit A
0:05 - Read Problem B
0:08 - Start coding B

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ICPC Routine

Member 1: Read A, B, C
Member 2: Read D, E, F
Member 3: Read G, H, I (or help with easier ones)

Immediately share: "A is easy [topic], B is [topic], etc."

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Reading Problems Effectively

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The 3-Read Method

1. Skim (30 seconds): What type of problem is this?
2. Detailed Read (2 minutes): Constraints, examples, edge cases
3. Verification (30 seconds): Reread the output format

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Constraint Analysis Cheat Sheet

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When You’re Stuck

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The 5-Minute Rule

1. Reread the problem - Did you miss something?
2. Check examples manually - Trace through by hand
3. Try small cases - n = 1, 2, 3
4. Consider related patterns - What technique does this remind you of?

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Escape Strategies

Stuck on implementation → Write pseudocode first
Stuck on approach → List all techniques that might apply
Stuck on edge cases → Think: 0, 1, -1, empty, maximum
Stuck on TLE → What's the bottleneck? Can you precompute?

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When to Skip

• You’ve spent 20+ minutes with no progress
• The problem type is unfamiliar
• Easier problems remain unsolved

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Debugging Under Pressure

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Prevention is Better

// Always use these before contest
#define int long long  // Prevent overflow bugs
const int INF = 1e18;  // Large enough for all cases

// Bounds check
assert(0 <= x && x < n);

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Stress Testing

// Generate random test
void generateTest() {
    int n = rand() % 100 + 1;
    // Generate random input
}

// Compare brute force with optimized
while (true) {
    auto input = generateTest();
    auto ans1 = bruteForce(input);
    auto ans2 = optimized(input);
    if (ans1 != ans2) {
        // Print failing test
        break;
    }
}

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Common Bug Checklist

• Integer overflow (use long long)
• Array index out of bounds
• Uninitialized variables
• Off-by-one errors
• Wrong variable name (copy-paste errors)
• Forgetting to reset globals between test cases
• 0-indexing vs 1-indexing mismatch

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Time Management

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Codeforces Time Budget (2 hours)

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Know When to Code vs Think

• Code immediately: You see the pattern clearly
• Think first: Novel problem, unclear approach
• Switch problems: Stuck 15+ minutes, others unsolved

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The CP-31 Checklist

1. Input/Output - Correct format? Flushed output?
2. Edge cases - n=0? n=1? Empty arrays?
3. Overflow - Need long long? Multiplication overflow?
4. Constraints - Does complexity fit time limit?
5. Array bounds - Enough space allocated?

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Post-Contest Analysis

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After Every Contest

1. Upsolve unsolved problems - This is where real learning happens
2. Analyze time spent - Where did you lose time?
3. Review wrong submissions - What caused them?
4. Tag problems by pattern - Build your pattern database

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Rating Goals and Practice

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Virtual Contests

Codeforces → Contests → Pick a past contest → "Virtual Participation" (right sidebar)
Or
Set 2-hour timer → No peeking at solutions

• No external resources (except template)
• No solution peeking
• Submit even if unsure
• Analyze performance afterward

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Building Your Template

#include <bits/stdc++.h>
using namespace std;

#define int long long
#define endl '\n'
#define all(x) (x).begin(), (x).end()
#define sz(x) (int)(x).size()

const int INF = 1e18;
const int MOD = 1e9 + 7;

void solve() {
    // Your solution here
}

signed main() {
    ios::sync_with_stdio(false);
    cin.tie(nullptr);
    
    int t = 1;
    cin >> t;  // Comment if single test
    
    while (t--) {
        solve();
    }
    
    return 0;
}

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Psychology of Competition

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Staying Calm

• Before contest: Light practice, don’t try new techniques
• During contest: One problem at a time, deep breaths
• After WA: Re-read problem, don’t panic-submit

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Managing Tilt

1. Take 30 seconds away from screen
2. Re-read problem from scratch
3. Ask: “What am I assuming that might be wrong?”

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The Growth Mindset

• Every contest teaches something
• Rating fluctuates—focus on learning
• Celebrate progress, not just wins

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ICPC-Specific Tips

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Team Coordination

Team Roles:
- Primary Coder: Best at typing/implementation
- Problem Picker: Reads all problems, decides order
- Specialist: Deep knowledge in specific areas

Communication:
- "I think A is [greedy/DP/graph]"
- "I need the computer in 5 minutes"
- "I'm stuck, can you look at this?"

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Coding Efficiency

• Print code for debugging
• One person codes, one reviews
• Use simple variable names for speed

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Codeforces-Specific Tips

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Rating Optimization

• Don’t oversubmit: Penalty adds up
• Lock early if confident: Extra points for others’ failures
• Check hacks during freeze: Learn from others’ approaches

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Handling Pretests vs System Tests

• Pretests are NOT comprehensive
• Always consider edge cases
• Stress test if time permits

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Your 30-Day Improvement Plan

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Key Takeaways

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Final Words

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Resources

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Essential Practice Sites

• Codeforces - Contests and problemset
• CSES Problem Set - Curated 300 problems
• AtCoder - High-quality problems
• LeetCode - Interview-style problems

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Learning Resources

• CP-Algorithms - Algorithm encyclopedia
• USACO Guide - Structured curriculum
• Codeforces EDU - Interactive courses

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Community

• Codeforces blogs and editorials
• Competitive Programming Discord servers
• ICPC practice with team