There is a square matrix 'X' of dimension n x n. It consists of zeros and ones. Given a value k, print the dimensions of a sub matrix of X consisting at most k zeros.

Given an array of size N and an integer K. You need to find the (sum of subsequence * GCD of that subsequence) over all K length subsequences of the given array A. Print the answer modulo 998244353. For e.g. A[] = {1, 2}, K = 1. Two subsequences of length 1 are {1} and {2}, then answer is 1*1 + 2*2 = 5

Given an array of N numbers and a number K find the maximum subarray size such that the average of the elements of the subarray >= k

You have a dictionary with set of words, you have to create a data structure which will give you no of words of length L whose ith character is C. Queries are very frequent, Try to optimize it. If possible, please do provide the code.