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Introduction

Welcome to the DSA handbook.

Now​

  1. 3 Sum, 4 Sum Duplicacy removal
  2. 2D BS and DFS, BFS
  3. Boyer–Moore majority vote algorithm
  4. gcd, xor

Dec 30, 2025​

Primary focus on all 13 problem of 1D Array

  1. Koko Eating Banans
  2. Search in Roated Sorted II
  3. Signle Element
  4. Minimum in Rotated Sorted Array
  5. Count rotation
  6. Find Peak Element
  7. Search Insert Position
  8. Find Square Root
  9. Maximum one's
  10. Search in 2D matrix

Dec 31, 2025​

Primary focus on all 9 problem of LL, DLL and Medium of DLL

  • Note Down current & current->next
  • Iterative & Recursive Reverse

Feb 1, 2025​

Primary focus on all 14 problem of array easy

Weaknesses​

  • 0 problems last year → severe inactivity.
  • Rating below 800 → likely:
    • Slow implementation
    • Panic during contests
    • Weak debugging discipline
    • Weak pattern recognition
    • Poor greedy reasoning

Likely Technical Gaps​

At 792 rating, typical weaknesses are:

  • Implementation errors (indexing, off-by-one)
  • Weak string manipulation
  • Poor condition handling
  • Not recognizing simple greedy patterns
  • Fear of math problems
  • No structured upsolving habit

You are likely failing mostly on:

  • 800–1000 problems
  • Div2 A occasionally
  • Div2 B rarely

Psychological Problems​

Based on inactivity pattern:

  • You probably binge-practiced once.
  • Rating dropped.
  • Motivation collapsed.
  • Long break.
  • Guilt cycle.

This is extremely common below 1000.

We fix this with structure.

30-DAY COMEBACK PLAN (792 → 1000)​

Goal: Reach stable 1000 rating.

We do NOT rush.

Daily Routine (Minimum 2 Hours)​

Weekdays (2 hours)

  1. Block 1 (60 min):
    • Solve 3 problems
    • Rating range: 800–1000
  2. Block 2 (30 min):
    • Review wrong submissions
    • Rewrite clean solution
  3. Block 3 (30 min):
    • Re-solve 1 previously solved problem WITHOUT looking
    • Total: 4 problems/day

Weekend (3–4 hours)

  • 1 Virtual Contest (Div3 preferred)
  • Upsolve all unsolved A/B after contest
  • Solve 2 extra 900–1100 problems

Topic Priority (First 30 Days)​

You must master these in order:

  1. Implementation
  2. Strings
  3. Basic greedy
  4. Math (gcd, parity, divisibility)
  5. Sorting
  6. Prefix sums
  7. Basic two pointers

Ignore DP. Ignore graphs. Ignore segment trees.

You are building foundations.

Weekly Target​

  • 20–25 problems/week
  • 2 virtual contests/week
  • 1 full review day

30 days → ~90 problems

This alone can push you to 1000.

Virtual Contest Strategy​

Only:

  • Div3
  • Old Div2 rounds (rated <1500 difficulty)

During contest:

  • 10 minutes max on A
  • 20 minutes max on B
  • Skip if stuck
  • NEVER spend 40 minutes on A

Upsolving Protocol (CRITICAL)​

After contest:

For each unsolved problem:

  1. Think 20 minutes.
  2. Read editorial.
  3. Re-implement without copying.
  4. Add to mistake log.

If you don’t upsolve, your rating will not grow.

Mistake Log Structure​

Create a Google Doc.

For each wrong problem write:

Problem Name:
Rating:
Type:
Mistake Type:

  • Logic?
  • Edge case?
  • Misread?
  • Implementation?
  • Math gap?

What pattern did I miss?

Review this every Sunday.

90-DAY GROWTH PLAN (1000 → 1300)​

Now we build real strength.

Topic Roadmap (Ordered)

  1. Greedy patterns
  2. Prefix sums advanced
  3. Binary search
  4. Two pointers deeper
  5. Constructive algorithms
  6. Basic combinatorics
  7. Intro DP (very basic 1D)
  8. Simple graphs (BFS/DFS)

Div2 A/B Mastery Strategy​

Goal: Solve A in 5–7 minutes.

Training method:

  • Take 30 random Div2 A (800–1000)
  • Solve all under time limit of 7 minutes each.

Then:

  • Take 40 problems rated 1000–1200.
  • Solve 2 daily.

Speed Training (3x/week)​

Set timer 45 minutes:

  • Solve 4 problems rated 900–1100.

Speed > difficulty.

Pattern Recognition Training​

After every problem ask:

  • Is this greedy?
  • Is this counting?
  • Is this prefix sum?
  • Is this simulation?
  • Is this constructive?

Classify every solved problem.

After 200 problems, patterns become automatic.

Weekly Structure (90-Day Phase)​

Monday–Friday:

  • 3 problems/day (1000–1200)

Saturday:

  • 1 virtual contest

Sunday:

  • Upsolve + review mistake log
  • Re-solve 2 old wrong problems

Target:

  • 15–18 problems/week
  • 1–2 contests/week

In 3 months → ~200 more problems

You will reach 1200–1300 if consistent.

6–12 MONTH PLAN (1300 → 1600+)​

Now you transition from beginner to structured thinker.

When to Start Advanced Topics​

Start learning seriously after 1200:

  • Binary search on answer
  • Graph BFS/DFS variations
  • Basic DP patterns
  • Greedy proof logic
  • Bit manipulation
  • Frequency maps

After 1400:

  • Segment tree
  • Basic number theory
  • 2D prefix sums
  • Shortest paths

Contest Strategy Evolution​

At 1300:

Goal per contest:

  • Solve A fast
  • Solve B confidently
  • Attempt C
  • Partial D thinking

Never rush D if B is shaky.

Studying Strong Coders​

Pick random 1500–1800 rated user.

After contest:

  • Open their submission.
  • Compare logic.
  • Check:
    • Variable naming
    • Code simplicity
    • Pattern recognition

Do this twice per week.

This accelerates growth massively.

EXACT PROBLEM-SOLVING FRAMEWORK​

How Long to Think?​

  • For 800–1000: 15 minutes max
  • For 1000–1200: 25 minutes max
  • If no direction → read editorial.
  • Struggling 1 hour teaches nothing.

When to Switch Problems​

If:

  • You feel stuck in implementation detail
  • You don’t know what the first step is
  • You tried 2 approaches

Switch immediately.

Debugging Faster​

Checklist:

  1. Edge case n=1?
  2. All equal values?
  3. Sorted input?
  4. Negative numbers?
  5. Overflow?
  6. Reset variables per test case?

90% of bugs are here.

Post-Contest Analysis Template

After contest write:

  1. Which problem wasted most time?
  2. Why?
  3. Did I panic?
  4. Was I slow reading?
  5. What pattern did I miss?
  6. What will I change next contest?

If you don’t do this, rating stagnates.

CONTEST STRATEGY FOR NEWBIES​

Time Allocation (Div3)​

0–10 min → A
10–30 → B
30–60 → C attempt
60–90 → fix bugs
Last 30 → re-check all submissions

When to Skip​

Skip if:

  • You don’t understand problem after 5 minutes.
  • You don’t know what data structure to use.

Skipping is strength, not weakness.

Risk Management​

Never submit without:

  • Testing 3 custom cases
  • Checking smallest input
  • Checking largest input

Avoid WA chains.

Avoid Tilt After WA​

Rule:

After 2 WAs:

  • Stop.
  • Reread entire problem.
  • Re-evaluate logic from scratch.

Do NOT randomly modify code.

Target Metrics:​

  • Month 1:
    • 90 problems
    • 8 contests
  • Month 3:
    • 250 total problems
    • Stable 1200 rating
  • Month 6:
    • 400–500 total problems
    • 1400+

PSYCHOLOGICAL DISCIPLINE PLAN​

This is the real battle.

Anti-Procrastination Rule​

Minimum rule:

  • Solve at least 1 problem daily.
  • Even on worst day.

Never break the chain twice.

Streak Rebuild Strategy​

Start 7-day streak.
Then 14.
Then 30.

You once did 15.
Now aim 30.

Handling Rating Drops​

Rule: Rating drop ≠ skill drop.

After bad contest:

  • Solve 3 easy problems immediately.
  • Regain confidence.

Never quit after a red contest.

Long-Term Motivation​

  • Shift goal: Not "increase rating".
  • Goal: “I solve 20 problems per week.”
  • Rating is a byproduct.

Final Reality Check​

You are 4 years registered. Rating 792.

If you continue randomly: In 4 more years → same result.

If you follow this strictly:

  • 1 month → 1000
  • 3 months → 1200+
  • 6–9 months → 1500
  • 1 year → 1600 possible

But only if you are consistent.

Your problem is not intelligence.

Your problem is structure.

Now build it.

Start today. Solve 3 problems. No excuses.