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.
Given two integers, left and right, representing a range [left, right], you need to calculate the bitwise AND of all numbers within that range, inclusive. The bitwise AND operation takes two numbers and returns a number where each bit is set to 1 if the corresponding bits of both numbers are also 1.
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.
Given an array of positive integers and a target value, find the minimal length of a contiguous subarray whose sum is greater than or equal to the target. If no such subarray exists, return 0.
