Freaks City

Maximum Meetings Attendance Given a list of meetings where each meeting is represented as [start, end], determine the largest number of meetings you can attend if you can only be in one meeting per day and you may pick any day within the inclusive interval [start, end] to attend that meeting. Intuition The key observation is that we want to fin ...

[NOIP2004 Advanced Group] Merging Fruits / [USACO06NOV] Fence Repair G Problem Description In an orchard, Duoduo has already knocked down all the fruits and divided them into different piles according to their types. Duoduo decides to merge all the fruits into one pile. Each time, Duoduo can merge two piles together, and the effort consumed equ ...

Find the Champion in an Array Game Given a distinct-integer array arr and an integer k, simulate a game where the first two elements compete in each round. The larger value wins, stays at index 0, and the smaller one is moved to the end. The game ends as soon as any value wins k consecutive rounds; that value is the champion. Examples arr = [2 ...

Number Theory Primality Testing via Trial Division #include <iostream> using namespace std; bool isPrime(int num) { if (num < 2) return false; for (int d = 2; d <= num / d; ++d) if (num % d == 0) return false; return true; } int main() { int queries; cin >> queries; while (queries--) { ...

A bracket string of even length consists of exactly n/2 opening [ and n/2 closing ] characters. The goal is to determine fewest number of arbitrary index swaps required to transform the string into a valid bracket sequence (one where every closing bracket has a matching opening bracket earlier in the string). Pairs of matched brackets can be t ...

Binary Search Implemantation Patterns Two common binary search variations address different optimization scenarios: Maximizing Minimum Value #include <iostream> #include <vector> #include <algorithm> using namespace std; bool validateMin(vector<long>& positions, long min_gap, int removals) { long prev = 0; i ...

Equalizing Card Piles (Greedy Approach) To distribute cards equally among $N$ piles, calculate the average number of cards per pile and subtract this value from each pile's count. This transforms the problem into finding the minimum number of moves to zero out the differences. Iterating from left to right, if a pile has a non-zero discrpeancy, ...

Problem Statement: Given positive integers $n$, $m$, and $m$ triplets $(l_i, r_i, c_i)$, we have an array $a_{1..n}$ initialized with zeros. For each operation $i = 1, ..., m$, perform the following steps: Choose any integer $k \in [0, c_i]$. Add $k$ to all elements $a_j$ where $j \in [l_i, r_i]$. Add $c_i - k$ to all elements $a_j$ where $j \ ...

Resource Redistribution with Asymmetric Operations Given a sequence (a) of length (n) and two positive integers (x, y) where (y \le x). You may repeatedly pick two elements and transfer resources: subtract (x) from one and add (y) to the other, provided the first remains non‑negative. Determine the maximum possible value of any element after op ...

Given an integer array nums, find and return the maximum sum of elements that is divisible by three. Examples Example 1: Input: nums = [3,6,5,1,8] Output: 18 Explanation: Choose numbers 3, 6, 1, and 8. Their sum is 18 (the maximum sum divisible by three). Example 2: Input: nums = [4] Output: 0 Explanation: 4 is not divisible by 3, so no number ...