You are given a number of cities and a list of flights between them. Each flight has a price and connects two cities. You need to find the cheapest route from a given source city to a destination city with at most a certain number of stops. If no such route exists, return -1.
You are given a directed acyclic graph (DAG) with n nodes, labeled from 0 to n-1. Find all possible paths from node 0 to node n-1 and return these paths in any order. The graph is represented such that each node has a list of other nodes that can be visited directly from it.
You are given a directed graph where each node represents a point, and edges represent possible transitions between nodes. A node is considered terminal if it has no outgoing edges. A node is deemed safe if every path starting from it leads either to a terminal node or another safe node. Your task is to identify all the safe nodes in the graph and return them in ascending order.
You are in a building with multiple rooms, each containing a set of keys to unlock other rooms. Initially, only the first room (room 0) is unlocked. You are tasked with determining whether you can visit all the rooms, starting from room 0. To enter a locked room, you must have its corresponding key, which can only be obtained by visiting other rooms.
Given a binary tree, a target node within the tree, and a non-negative integer k, determine all the nodes that are exactly k edges away from the target node. Return these node values as a list in any order.
Given the root of a binary tree, return the smallest subtree that contains all the nodes with the maximum depth in the tree. A node is considered the deepest if it has the greatest distance to the root among all nodes. The subtree of a node consists of the node itself and all its descendants.
