🚀 Competitive Programming & Algorithmic Problem Solving

A comprehensive repository containing 900+ competitive programming & algorithmic solutions, verified CP templates, and theoretical cheat sheets by Pratham Kashyap.

👤 Profiles • Codeforces • LeetCode • CSES • CodeChef • HackerEarth • HackerRank • AtCoder • Templates • Notes

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👤 Competitive Programming Profiles & Standings

Platform	Profile Link	Handle / Username	Key Rating / Standing	Solved Count	Prestigious Badges & Honors
LeetCode	prathamkashyap	@prathamkashyap	Top Active Users	401+ Solved (141 Easy • 206 Med • 54 Hard)	🎖️ High Accuracy (~85% AC Rate) 🔥 Consistent Daily Streaks
Codeforces	prathamkashyap	@prathamkashyap	Rating: 1184 (Newbie)	250+ Solved (Rating 800 – 2000+)	🏆 Active Contestant ⚡ Div. 2 / Div. 3 Regular
CodeChef	prathamkashyap	@prathamkashyap	1★ (Div 4) (DSA Rating: 1067)	217+ Solved	🥈 Silver League Member 🎯 Starters & DSA Munch Finisher
HackerEarth	prathamkashyap	@prathamkashyap	Global Explorer	Practice Tracks	🏆 Top 2% in Basic Programming 🎖️ Novice, Amateur, Explorer
HackerRank	prathamkashyap	@prathamkashyap	Certified Developer	Domain Tracks	⭐ Problem Solving & Language Stars

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📊 Solved Problems Matrix

┌─────────────────┬──────────┬─────────────────────────────────────────────────┐
│ Platform        │  Solved  │ Difficulty Distribution / Progress               │
├─────────────────┼──────────┼─────────────────────────────────────────────────┤
│ LeetCode        │   401+   │ 🟢 141 Easy  🟡 206 Medium  🔴 54 Hard           │
│ Codeforces      │   257+   │ 800: 83 │ 900: 37 │ 1000: 32 │ 1100: 19 │ 1200: 31│
│                 │          │ 1300: 30│ 1400: 5  │ 1500: 7  │ 1700+: 3 │ Contests: 30│
│ CodeChef        │   217+   │ Starters 197, 242, 250, DSA Challenges, Practice│
│ HackerEarth     │   Top 2% │ Basic Programming, Algorithms, Data Structures  │
│ HackerRank      │  Active  │ C++, Java, Python, Problem Solving Tracks       │
├─────────────────┼──────────┼─────────────────────────────────────────────────┤
│ TOTAL SOLVED    │   900+   │ Solutions across all platforms & repositories   │
└─────────────────┴──────────┴─────────────────────────────────────────────────┘

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📂 Repository Structure

competitive-programming/
├── codeforces/          # Solutions categorized by difficulty rating (800 - 2000+)
│   ├── 800/             # Fundamental implementation & greedy (83 solutions)
│   ├── 900/             # Math, string manipulation, brute force (37 solutions)
│   ├── 1000/            # Constructive algorithms, sorting, two pointers (32 solutions)
│   ├── 1100/            # Number theory, prefix sums, binary search (19 solutions)
│   ├── 1200/            # DP basics, greedy, combinatorics (31 solutions)
│   ├── 1300/            # Graph basics, modulo arithmetic, bitmasks (30 solutions)
│   ├── 1400/            # Medium DP, tree traversals, two pointers (5 solutions)
│   ├── 1500/            # Graphs (BFS/DFS), data structures (7 solutions)
│   ├── 1600/            # Advanced greedy, dynamic programming
│   ├── 1700/            # Range queries, segment trees
│   ├── 1800/            # Disjoint Set Union, game theory
│   ├── 2000/            # Complex DP, segment trees, mathematical proofs
│   └── unrated_questions/# Contest problems & live virtual submissions (30 solutions)
├── leetcode/            # LeetCode solutions categorized by topic & pattern
├── cses/                # Solutions to the CSES Problem Set
├── atcoder/             # Solutions to AtCoder Beginner (ABC) & Regular (ARC) Contests
├── codechef/            # Solutions to CodeChef Starters & Cook-Offs
├── hackerearth/         # Solutions to HackerEarth practice tracks & circuits
├── hackerrank/          # Solutions to HackerRank domain & certification tracks
├── templates/           # Production-ready CP boilerplate & data structure templates
│   ├── cpp/             # C++ Fast I/O, DSU, Segment Tree, Sieve, Fenwick Tree
│   ├── python/          # Python fast I/O & math utility templates
│   └── java/            # Java FastScanner & FastWriter templates
└── notes/               # Curated algorithmic notes, cheat sheets & complexity tables

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⚡ Quick Start & Compilation

C++20 Standard Build Flag

g++ -std=c++20 -O2 -Wall -Wextra -Wshadow -DLOCAL solution.cpp -o solution
./solution < input.txt

Fast I/O Snippet

#include <iostream>
using namespace std;

void fast_io() {
    ios_base::sync_with_stdio(false);
    cin.tie(nullptr);
    cout.tie(nullptr);
}

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🛠️ Production-Ready CP Templates

Located in /templates:

Template	Language	Complexity	Direct Link
Fast I/O & Universal CP Boilerplate	C++20	$O(1)$	template.cpp
Disjoint Set Union (DSU)	C++20	$O(\alpha(N)) \approx O(1)$	dsu.cpp
Segment Tree (Point Update, Range Query)	C++20	$O(\log N)$	segment_tree.cpp
Fenwick Tree (Binary Indexed Tree)	C++20	$O(\log N)$	fenwick_tree.cpp
Linear Sieve & Prime Factorization (SPF)	C++20	$O(N)$ build, $O(\log K)$ factor	sieve_prime.cpp
Python CP Template	Python 3	Optimized Fast I/O	template.py
Java CP Template	Java	Custom FastScanner & FastWriter	Template.java

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📖 Theory & Cheat Sheets

Explore quick revision guides in /notes:

• ⏱️ Time Complexity & Resource Limits - Operations per second ($10^8$), integer boundaries, and memory limits.
• 🔢 Number Theory & Modular Arithmetic - Fermat's Little Theorem, modular inverse, and $nCr \pmod p$.
• 💻 Bit Manipulation Hacks - Bitmask operations, subset generation, and GCC builtins (__builtin_popcount, __builtin_clz).
• 🌲 Graph Theory & Tree Algorithms - BFS, DFS, Dijkstra, Bellman-Ford, Floyd-Warshall, Kruskal, and LCA.
• 💡 Dynamic Programming Patterns - 0/1 Knapsack, LIS ($O(N \log N)$), LCS, Grid DP, and Space Optimization.

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🤝 Connect & License

• GitHub: @prathamkashyap
• LinkedIn: Pratham Kashyap
• LeetCode: prathamkashyap
• Codeforces: prathamkashyap
• CodeChef: prathamkashyap
• HackerEarth: prathamkashyap
• HackerRank: prathamkashyap

This project is licensed under the MIT License - see the LICENSE file for details.

_{Designed & Maintained with 💻 and ☕ by Pratham Kashyap.}