There are n houses in a village. We want to supply water for all the houses by building wells and laying pipes. For each house i, we can either build a well inside it directly with cost wells[i - 1] (note the -1 due to 0-indexing), or pipe in water…

You are given an array of variable pairs equations and an array of real numbers values, where equations[i] = [Ai, Bi] and values[i] represent the equation Ai / Bi = values[i]. Each Ai or Bi is a string that represents a single variable. You are also given some queries, where…

There are 3 types of channels: Logical channels. Logical channels transfer data between RLC and MAC layer. This data is called RLC PDU. CCCH(Common Control channel), DCCH (Dedicated control channel) and DTCH(Dedicated traffic channel) are uplink logical channels mapped to ULSCH transport channel. CCCH and DCCH are used to transfer…

Problem statement You are given a string s, and an array of pairs of indices in the string pairs where pairs[i] = [a, b] indicates 2 indices(0-indexed) of the string. You can swap the characters at any pair of indices in the given pairs any number of times. Return the…

Problem statement: You have a graph of n nodes. You are given an integer n and an array edges where edges[i] = [ai, bi] indicates that there is an edge between ai and bi in the graph. Return the number of connected components in the graph. This is another example…

Problem statement You have a graph of n nodes labeled from 0 to n - 1. You are given an integer n and a list of edges where edges[i] = [ai, bi] indicates that there is an undirected edge between nodes ai and bi in the graph. Return true if…

This is one important concept for grouping problems. I read all, then started doing the first problem and confused like how to do it. This concept is related to graphs or not graphs but there are a set of nodes or vertices where some vertices are grouped and some or…

Problem: You are given the root of a binary tree. We install cameras on the tree nodes where each camera at a node can monitor its parent, itself, and its immediate children. Return the minimum number of cameras needed to monitor all nodes of the tree. Never expected such a…

Another trees related problem :) A path in a binary tree is a sequence of nodes where each pair of adjacent nodes in the sequence has an edge connecting them. A node can only appear in the sequence at most once. …