http://codeforces.com/contest/30/problem/C 题意：给出n个target在一个二维平面上。给出每个target的坐标，出现的时间，以及击中的概率。target出现之后就会瞬间消失，枪移动的单位速度为1，射击不需要时间。问能击中的target的最大期望是多少。 思路：路径dp。。。按照时间升序排列。 dp[i]表示到第i个target出现的时候的期望。 /* *********************************************** Author :111qqz Created Time :2015年12月29日 星期二 18时14分45秒 File Name …

Desiderium **Time Limit: 4000/2000 MS (Java/Others) Memory Limit: 65536/65536 K (Java/Others) Total Submission(s): 427 Accepted Submission(s): 167 ** Problem Description There is a set of intervals, the size of this set is n. If we select a subset of this set with equal probability, how many the expected length of …

B. Andrey and Problem time limit per test 2 seconds memory limit per test 256 megabytes input standard input output standard output Andrey needs one more problem to conduct a programming contest. He has n friends who are always willing to help. He can ask some of them to come up with a contest problem. Andrey knows one …