Contest OverviewMisreading the first problem caused a 20-minute delay. The second problem presented a psychological barrier despite being solvable for partial points. Skipping the third problem's statement cost easy points, while the fourth problem failed due to inefficient modular inverse preproces...
Single-width adjacent caves in a row each hold some gold coins. A fixed-width stone door, initially blocking three unspecified caves, can be shifted exactly once to cover any set of three consecutive caves. No cave can be accessed before shifting; after shifting, only unblocked caves are collectible...
Scholarship Allocation A school distributes scholarships after each semester's final exams. There are five scholarship types available: Academician Scholarship: 8000 yuan for students with final exam scores > 80 and atleast one published paper May Fourth Scholarship: 4000 yuan for students with f...
Determining Valid Initial Values for Tree Path ConstraintsLet v represent the cumulative change in value from the root to a specific node u. For the initial value x to remain valid when reaching u, it must satisfy the constraint L_u - v <= x <= R_u - v. The cumulative change v can be managed e...
Problem A – Kamilka’s Sheep and the Optimal Boost Given n distinct positive integers a1, a2, …, an, choose a non–negative integer d and add d to every element. After the increment, pick any two resulting values x and y and compute gcd(x, y). The goal is to maximize this greatest common divisor. Key...
Problem A: Building Height Comparison Given an array of building heights, find the first building taller than the first one. #include <cstdio> const int MAX_SIZE = 105; int heights[MAX_SIZE]; int main() { int n; scanf("%d", &n); int result = -1; for (int i = 1; i <= n; i++) {...
Problem A: Minimum Function Summation Given the function f(x) = min_{i∈ℕ⁺}, compute the sum Σ_{i=1}^{n} f(i) modulo 10^9+7 across multiple test cases. Constraints: n ≤ 10^16, T ≤ 10^4. Solution Approach: Analyze the frequency of each value in the sequence f(i). For a particular value x, we need to c...
Problem A: Locating the Singleton Character Concept: Given a string containing exactly two distinct lowercase letters, identify the 1-based index of the letter that appears precisely once. Approach: Maintain frequency counters or index lists for each character. Since only two characters exist in the...
The problem requires counting the number of valid sequences \(b\) given constraints \(b_i \in [L_i, R_i]\) and a similarity condition defined by a sequence \(a\). Two sequences \(a\) and \(b\) are defined as "k-similar" if, for every quadruple \((l_1, r_1, l_2, r_2)\) where the intervals \([l_1, r_1...
A — Checking a Beautiful Arrangement Three pillars stand equally spaced in a line. Their heights are (a), (b), (c) from left to right. The arrangement is beautiful if (b - a = c - b). Determine whether it qualifies. #include <iostream> int main() { int h1, h2, h3; std::cin >> h1 >>...