Given a singly linked list, implement a class that supports the initialization of the list and the ability to return a random node’s value with equal probability.
Given an integer array nums with potential duplicates, you need to randomly select an index i where nums[i] == target. If there are multiple indices with the same value, the selection should be made with equal probability for each valid index.
You are given an array of non-overlapping axis-aligned rectangles. Each rectangle is represented by its bottom-left and top-right corner. Your task is to design a system that can pick a random integer point from the space covered by one of the given rectangles. A point on the perimeter of a rectangle is considered inside the rectangle.
You are given a binary grid of size m x n, where each cell is initially set to 0. The task is to design an algorithm that can randomly pick a cell that is still 0, flip it to 1, and ensure that all available cells are equally likely to be selected.
