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第一题： A. Olympiad time limit per test 1 second memory limit per test 256 megabytes input standard input output standard output The recent All-Berland Olympiad in Informatics featured n partic...

题目链接：http://codeforces.com/contest/810/problem/C 题目大意： 告诉你一个含有n个互不相同的元素的集合，求它的所有非空子集中元素最大值与元素最小值之差的和。结果很大，输出它%1e9+7后的结果。 推倒： 先对A排序，然后不妨枚举子集的最小元素，看一下它对答案的贡献 考虑一个数列1 3 5 7 9，假设1是子集的最小元素 再考虑集合的最大元素...

codeforces 615A. Bulbs A. Bulbs time limit per test 1 second memory limit per test 256 megabytes input standard input output standard output Vasya wants to turn on Christmas lights consistin...

B. New Year and North Pole time limit per test 2 seconds memory limit per test 256 megabytes input standard input output standard output In this problem we assume the Earth to be a completely...

A. New Year and Hurry time limit per test 1 second memory limit per test 256 megabytes input standard input output standard output Limak is going to participate in a contest on the last day o...

A. Santa Claus and Candies time limit per test 1 second memory limit per test 256 megabytes input standard input output standard output Santa Claus has n candies, he dreams to give them as gi...

A. Crazy Computer time limit per test2 seconds memory limit per test256 megabytes inputstandard input outputstandard output ZS the Coder is coding on a crazy computer. If you don’t type in a word...

A. Buy a Shovel time limit per test 1 second memory limit per test 256 megabytes input standard input output standard output Polycarp urgently needs a shovel! He comes to the shop and chooses...

题目：A. Restoring Numbers Pavel had two positive integers a and b. He found their sum s and greatest common divisor g, and forgot a and b after that. Help him to restore the original numbers. Input A ...