Consider a set A = {a1, . . . , an} and a collection B1, B2, . . . , Bm of subsets of A (i. e., Bi ⊆ A for each i). We say that a set H ⊆ A is a hitting set for the collection B1, B2, . . . , Bm if H contains at least one element from each Bi – that is, if H ∩ Bi is not empty for each i (so H "hits" all the sets of Bi). We define the Hitting Set Problem as follows. We are given a set A = {a1, . . . , an}, a collection B1, B2, . . . , Bm of subsets of A, and an non-negative integer k. We are asked: is there a hitting set H ⊆ A for B1, B2, . . . , Bm so that the size of H is at most k? Prove that the Hitting Set problem is NP-complete

Working on this program in python 3.7: a year in the modern gregorian calendar consists of 365 days. in reality, the earth takes longer to rotate around the sun. to account for the difference in time, every 4 years, a leap year takes place. a leap year is when a year has 366 days: an extra day, february 29th. the requirements for a given year to be a leap year are: 1) the year must be divisible by 42) if the year is a century year (1700, 1800, the year must be evenly divisible by 400some example leap years are 1600, 1712, and 2016.write a program that takes in a year and determines whether that year is a leap year.ex: if the input is 1712, the output is: 1712 is a leap year. ex: if the input is 1913, the output is: 1913 is not a leap year. your program must define and call the function isleapyear(useryear). the function should return true if the input year is a leap year and false otherwise.

Suppose s, t, and w are strings that have already been created inside main. write a statement or statements, to be added to main, that will determine if the lengths of the three strings are in order by length, smallest to largest. that is, your code should determine if s is strictly shorter than t, and if t is strictly shorter than w. if these conditions hold your code should print (the boolean value) true. if not, your code should print false. (strictly means: no ties) example: if s, t, and w are "cat", "hats", and "skies" your code should print true - their lengths are 3-4-5; but if s, t, and w are "cats" "shirt", and "trust", then print false - their lengths are 4-5-5 enter your code in the box below

Jason works as an accountant in a department store. he needs to keep a daily record of all the invoices issued by the store. which file naming convention would him the most?