Description As we know, any positive integer C ( C >= 2 ) can be written as the multiply of some prime numbers: C = p1×p2× p3× ... × pk which p1, p2 ... pk are all prime numbers.For example, if C = 24, then: 24 = 2 × 2 × 2 × 3 here, p…
Description Edward has a set of n integers {a1, a2,...,an}. He randomly picks a nonempty subset {x1, x2,…,xm} (each nonempty subset has equal probability to be picked), and would like to know the expectation of [gcd(x1, x2,…,xm)]k. Note that gcd(x1, …
Description Alice is playing a game with Bob. Alice shows N integers a 1, a 2, …, a N, and M, K. She says each integers 1 ≤ a i ≤ M. And now Alice wants to ask for each d = 1 to M, how many different sequences b 1, b 2, …, b N. which satisfies : 1. F…
Description A lattice point (x, y) in the first quadrant (x and y are integers greater than or equal to 0), other than the origin, is visible from the origin if the line from (0, 0) to (x, y) does not pass through any other lattice point. For example…
Description Given 5 integers: a, b, c, d, k, you're to find x in a...b, y in c...d that GCD(x, y) = k. GCD(x, y) means the greatest common divisor of x and y. Since the number of choices may be very large, you're only required to output the total num…
