ACM文档1.ppt

Comments on the previous exercises The 3n+1 problem /JudgeOnline/showproblem?problem_id=1027 This is an outstanding unsolved problems in number theory, called 3n+1 conjecture. Start with an integer n; If n is even, n=n/2; else n = 3n+1; Repeat this process, terminating when n=1. It’s conjectured that this algorithm will terminate at n=1 for every integer n. E.g.: 22 11 34 17 52 26 13 40 20 10 5 16 8 4 2 1 The “cycle length” for 22 is 16. 3n+1 problem Write a function to calculate the “cycle length” for integer i The trip http://acm.uva.es/p/v101/10137.html A number of students are members of a club that travels annually to exotic locations. The group agrees in advance to share expenses equally, but it is not practical to have them share every expense as it occurs. So individuals in the group pay for particular things, like meals, hotels, taxi rides, plane tickets, etc. After the trip, each students expenses are tallied and money is exchanged so that the net cost to each is the same, to within one cent. In the past, this money exchange has been tedious and time consuming. Your job is to compute, from a list of expenses, the minimum amount of money that must change hands in order to equalize (within a cent) all the students costs. The trip (Cont.) The Input Standard input will contain the information for several trips. There are no more than 1000 students and no student spent more than $10,000.00. A single line containing 0 follows the information for the last trip. The Output For each trip, output a line stating the total amount of money, in dollars and cents, that must be exchanged to equalize the students costs. The trip (Cont.) It’s important to analyze the problem first. After you find the optimal way which can achieve the “minimum amount of money that must change hands”, writing the program will be very easy. What’s the difficulty of this problem? We need to equalize the costs as much as possible. That means: if A pays the most, and A pays PA; if B pay