Fading Coder

One Final Commit for the Last Sprint

AtCoder Beginner Contest 050 Problem Solutions

The input consists of an arithmetic expression in the form a + b or a - b. Parse the expression and output the computed result. int main() { int operand1, operand2; char operation; std::cin >> operand1 >> operation >> operand2; if (operation == '+') { std::cout << operand1 +...

Advanced Range Query Techniques: Sqrt Decomposition and Mo's Algorithm Enhancements

Optimizing Subarray Frequency Queries Determining the most frequent element's count within arbitrary subranges presents a challenge for standard data structures due to non-additive merge properties. While segment trees struggle here, offline processing via Mo's algorithm (square root decomposition o...

Competitive Programming Contest Problems and Solutions

A. Triangle Construction with Guaranteed Validity Given four strictly increasing integers a < b < c < d, select three values x, y, z such that they form a non-degenerate triangle — i.e., satisfy the strict triangle inequality x + y > z. Since all inputs are ordered, the safest choice is...

Solving Linear Congruence Equations with Extended Euclidean Algorithm

The Extended Euclidean Algorithm is a fundamental tool for solving linear Diophantine equations of the form ax + by = gcd(a, b). This technique is frequently required in competitive programming to solve problems involving modular arithmetic and periodic patterns, such as the classic "Frog's Mee...

Meituan 2024 Spring Campus Recruitment - Software Engineering Positions - First Round Online Assessment

Problem Set Overview This article presents solutions to five algorithmic problems from Meituan's 2024 Spring campus recruitment online assessment for software engineering positions. Each problem requires specific algorithmic techniques ranging from prefix sum optimization to union-find data structur...

HTTP Header Parsing and Tree-Based MEX Queries in Competitive Programming

This article presents concise, robust solutions to two distinct algorithmic problems from a competitive programming context: parsing and decoding HTTP-like header structures using Huffman tree reconstruction, and computing the minimum excluded value (MEX) on tree paths via persistent segment trees....

Interval DP Solution for Splitting and Merging Problem

Problem Analysis This problem requires splitting and merging intervals with maximum profit. The solution naturally fits the interval dynamic programming paradigm. DP Formulation For any interval [l, r], we choose a split point j (where l ≤ j < r) and split it into two subintervals: [l, j] and [j+...

Efficient Conflict Resolution in Array Pairing Problems

D. Prefix Reversal Construction A palindrome insertion strategy can transform any sequence by reversing prefixes. Inserting a pattern like abc...cba after a prefix abc... effectively reverses that prefix while leaving subsequent elements unchanged. Key insight: Two flip operations suffice for transf...

Algorithm Template Library: Data Structures and Graph Theory

Data Structures Mo's Algorithm Standard Mo's Algorithm Used to solve problems like P1494 [National Training Team] Little Z's Socks. #include <bits/stdc++.h> #define int long long using namespace std; const int MAXN = 200010; struct Query { int l, r, idx; }; struct Fraction { int numerator, den...

Subset Dynamic Programming: Code Analysis & Evaluation

Given an enteger grid of dimensions $R \times C$ ($R \leq 12$, $C \leq 2000$), the optimization objective is to assign disjoint subsets of row indices to a selected group of columns. Each assigned column may undergo an independent vertical cyclic shift. The contribution of a column to its allocated...