You are given a binary string s and a positive integer k. Your task is to find the length of the longest subsequence of s that represents a binary number less than or equal to k when converted to decimal.
You are given an undirected graph with n nodes and a list of edges connecting the nodes. The goal is to find the number of pairs of distinct nodes that are unreachable from each other.
You are given an integer array nums. In each operation, select a non-negative integer x and an index i, then update nums[i] to be equal to nums[i] AND (nums[i] XOR x). The task is to find the maximum possible bitwise XOR of all elements after applying the operation any number of times.
Given a street with two rows of plots, each containing n plots, find the number of ways houses can be placed such that no two houses are adjacent on the same side of the street. Return the result modulo 10^9 + 7.
You are given two integers, m and n, which represent the dimensions of a matrix. You are also given the head of a linked list of integers. Your task is to generate an m x n matrix by filling it in a spiral order (clockwise) using the integers from the linked list. If any spaces remain, fill them with -1.
On day 1, one person discovers a secret. Each person will share the secret after a delay and forget it after a certain number of days. Return the number of people who know the secret at the end of day n, modulo 10^9 + 7.