You are given a perfect binary tree where every parent node has two children and all leaves are at the same level. Your task is to populate the ’next’ pointer of each node to point to its next right node. If no such node exists, set the ’next’ pointer to NULL. Initially, all ’next’ pointers are set to NULL.
You are given an m x n matrix board containing letters ‘X’ and ‘O’. Capture all regions that are surrounded by ‘X’. A region is captured if it is surrounded by ‘X’ cells and cannot reach the edges of the board.
You are given a reference to a node in a connected, undirected graph. Each node in the graph contains a value (integer) and a list of its neighbors. Your task is to return a deep copy of the entire graph starting from the given node.
You are given the root of a binary tree. Imagine yourself standing on the right side of the tree, and return the values of the nodes you can see when viewed from the right, ordered from top to bottom.
You are given a 2D grid representing a map, where ‘1’ represents land and ‘0’ represents water. Your task is to count how many islands are formed by connecting adjacent lands horizontally or vertically. An island is a collection of ‘1’s connected either horizontally or vertically.
You are given a set of courses and a list of prerequisites. Each prerequisite is a pair of courses where the second course must be taken before the first one. Determine if it is possible to complete all courses based on these prerequisites. If there are cycles in the dependencies, it would be impossible to finish all courses.
