Freaks City

To determine which edges can lie on a shortest path from source S to target T in a directed graph, compute shortest distances from S to all nodes. Then, perform a reverse BFS starting from T on the transposed graph. For each dequeued node cur and its neighbor nex in the transposed graph, if Dist[nex] == Dist[cur] - weight(cur->nex) holds, th ...

Binary search operates with O(log n) time complexity on a sorted array of n elements. The algorithm repeatedly divides the search interval in half, achieving logarithmic performance. Algorithm Fundamentals Binary search, also known as half-interval search, is an efficient algorithm for locating a target value within a sorted sequence. It compar ...

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 ...

Trpaping Rain Water Problem Given an array representing elevation maps, this problem calculates how much water can be trapped between bars after raining. vector<int> leftMax(n, 0); vector<int> rightMax(n, 0); if (n == 0) return 0; leftMax[0] = height[0]; rightMax[n-1] = height[n-1]; for (int i = 1; i < n; ++i) { leftMax[i] = ...

Secret Code Decoding Recover Chinese character bitmaps from byte sequences and interpret hidden messages. Each character is represented by 32 bytes arranged in 16 rows of 2 bytes. Convert byte values to binary, replacing 0s with spaces to visualize the characters. Constraints Max runtime: 1 second Max memory: 128MB <java> public class B ...

Method 1: Square then Sort This approach squares each element first and subsequently sorts the resulting array. #include <stdio.h> #include <stdlib.h> int compareElements(const void* first, const void* second) { int elemA = *((int*)first); int elemB = *((int*)second); if (elemA < elemB) return -1; if (elemA > elemB) r ...

Problem StatementGiven an array of integers sorted in non-decreasing order, identify the starting and ending index of a specified target value. If the target is absent from the array, return [-1, -1]. The solution must operate with a logarithmic time complexity of O(log n).Expected OutcomesFor data = [5, 7, 7, 8, 8, 10], target = 8, the output ...

A stack is a linear collection that restricts element access to a single endpoint, commonly referred to as the top. This constraint enforces a Last-In-First-Out (LIFO) ordering, meaning the most recently added item is always the first to be removed. The two fundamental operations are push (insertion at the top) and pop (removal from the top). A ...

Python sets utilize a hash table implementation to store unique elements. The deduplication mechanism operates through a two-step verification process involving the __hash__ and __eq__ methods of the stored objects. Initially, the set evaluates the hash value of the incoming object. If this hash does not exist in the current hash table, the obj ...

977. Squares of a Sorted Array Problem Link on LeetCode Approach: Two Pointers Technique Since the array may contain negative numbers, we use two pointers to compare the squares of the elements from both ends. The left pointer starts at the beginning of the array, and the right pointer starts at the end. The larger square is placed at the curre ...