You are given an array of integers. Your task is to reorder the array such that the elements alternate between smaller and larger numbers. The sequence should follow the pattern nums[0] < nums[1] > nums[2] < nums[3] > nums[4]….
Given an integer a and an array b, where b represents a very large number, compute ( a^b % 1337 ). The array b stores the digits of b from most significant to least significant. You must handle extremely large values of b efficiently.
Given a string s and an integer k, return the length of the longest substring of s such that the frequency of each character in this substring is greater than or equal to k. If no such substring exists, return 0.
You are given an n x n binary grid of 0’s and 1’s. Your task is to represent this grid with a Quad-Tree. A Quad-Tree is a tree structure where each node has four children. Each internal node has two properties: val (True for a grid of 1’s or False for a grid of 0’s) and isLeaf (True if the node is a leaf, False if it has children). If the entire grid has the same value, the node is a leaf. If not, the grid is divided into four sub-grids, and the process is repeated recursively for each sub-grid. Your goal is to return the root of the Quad-Tree that represents the grid.
