Code-Forces Solutions Repository

A personal collection of competitive programming solutions, primarily targeting Codeforces problems. The repository contains 1,000+ solution files spanning beginner to advanced difficulty levels.

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Repository Structure

Code-Forces/
├── *.cpp / *.java        # Root-level solutions (56 C++ files, 1 Java file)
├── CFs/                  # Main archive of ~954 Codeforces solutions
│   ├── *.cpp             # C++ solutions (majority)
│   ├── *.py              # Python solutions
│   ├── *.java            # Java solutions
│   ├── *.js              # JavaScript solutions
│   ├── input.txt         # Sample test input
│   └── output.txt        # Sample test output
├── Others/
│   └── CPS Contests/     # Solutions from CPS-specific contest series
├── .vscode/              # VSCode editor configuration (C/C++ build & debug)
├── .cph/                 # Competitive Programming Helper (CPH) cache
└── .gitignore

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Languages Used

Language	Usage
C++	~99% — primary language for all competition problems
Python	Occasional alternative solutions
Java	Minimal (one practice file)
JavaScript	Minimal

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Solution Categories

Problems are organized by difficulty level (A = easiest, H = hardest) and cover a wide range of algorithmic topics:

Mathematics & Number Theory

• Prime generation (Sieve of Eratosthenes, N-th prime)
• GCD / LCM comparisons
• Pascal's Triangle
• Digit manipulation
• Modular arithmetic

Arrays & Sequences

• Subarray sums, subset sums, pair sums
• Difference arrays
• Sliding window technique
• Maximum subarray problems

Strings

• String transformations and mappings
• Diversity/validity checks
• Concatenation optimization

Bit Manipulation & XOR

• XOR on subarrays
• Reverse XOR
• XOR game problems

Greedy & Sorting

• Pair selection under constraints
• Distribution / assignment problems
• Inversions

Dynamic Programming & Search

• Dungeon / path-finding problems
• Sequence reconstruction
• Multi-dimensional DP

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Common Code Pattern

Nearly every solution follows the standard competitive programming template:

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

int main() {
    ios_base::sync_with_stdio(false);
    cin.tie(NULL);
    // solution logic
}

Some solutions also use GNU Policy-Based Data Structures for ordered sets:

#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/tree_policy.hpp>
using namespace __gnu_pbds;
typedef tree<int, null_type, less<int>, rb_tree_tag, tree_order_statistics_node_update> ordered_set;

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Build & Run

Solutions are compiled with g++ (C++17):

g++ -std=c++17 -O2 -o solution solution.cpp
./solution < input.txt

The .vscode/tasks.json provides a one-click build task inside Visual Studio Code.

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Key Difficulty Breakdown (Root-Level Files)

Level	Count	Description
A	18	Easy — brute force / basic math
B	15	Medium-Easy — simple algorithms
C	6	Medium — intermediate techniques
D	1	Hard — advanced algorithms
H	1	Very Hard — complex problem-solving