Freaks City

Given a binary tree, we need to install cameras on its nodes. Each camera can monitor its parent, itself, and its immediate children. The goal is to determine the minimum number of cameras reuqired to cover the entire tree. Problem Constraints Number of nodes ranges from 1 to 1000. Node values are irrelevant (typically 0). Core Strategy The o ...

A. Programming Contest This problem is a straightforward implementation task. The idea is to count the number of valid years betweeen two given years, excluding specific invalid years provided in the input. void solve() { int n, m; std::cin >> n; std::vector<int> invalidYearFlag(10000, 0); // Assuming a safe upper bound ...

Problem Overview: The 0/1 Knapsack Given a maximum capacity (or time limit) W and N distinct items, where each item has a weight (or time cost) and a value, the objective is to maximize the total value of selected items without exceeding the given capacity. Each item can be chosen at most once. Constraints Maximum Capacity W: 1 ≤ W ≤ 1000 Numb ...

Problem Description N aircraft are preparing to land at an airport with only one runway. The i-th aircraft arrives above the airport at time Ti and has enough remaining fuel to continue circling for Di units of time. This means it can begin landing at the earleist at time Ti, and at the latest at time Ti + Di. The landing process itself require ...

Constructing Binary Trees from Inorder and Preorder TraversalsGiven the preorder and inorder traversal sequences of a binary tree, the tree structure can be uniquely reconstructed. The first element in the preorder sequence always represents the root of the current subtree. By locating this root value within the inorder sequence, one can partit ...

Binary trees serve as foundational structures for many advanced topics such as dynamic programming and backtracking. Mastery of their traversal methods is essential. Core Traversal Strategies Two primary strategies exist: depth-first and breadth-first. Depth-First Traversal Explores as far as possible along each branch before backtracking. Vari ...

Given an m x n board of characters and a list of strings words, return all words on the board. Each word must be constructed from letters of sequentially adjacent cells, where adjacent cells are horizontally or vertically neighboring. The same letter cell may not be used more than once in a word. 1. Trie with DFS Build a trie from the given wor ...