这题思路很简单,二分m,求最大流是否大于等于x. 但是比赛过程中大部分的代码都被hack了... 精度问题,和流量可能超int 关于精度问题,这题真是提醒的到位,如果是先用二分将精度控制在10^-8左右,最后乘一个10^4,精度只能在10-4,而二分控制精度在10^-11很容易死循环(因为double 保存15-16位有效数字,结果可能为10^6级,精确到10-11,double做不到) 所以这题二分可以不写成while(d-b>eps),而直接规定二分的次数,设置成100次,基本可以保证14-…

B. Bear and Compressing 题目链接  Problem - B - Codeforces   Limak is a little polar bear. Polar bears hate long strings and thus they like to compress them. You should also know that Limak is so young that he knows only first six letters of the English…

E - Bear and Forgotten Tree 2 思路:先不考虑1这个点,求有多少个连通块,每个连通块里有多少个点能和1连,这样就能确定1的度数的上下界. 求连通块用链表维护. #include<bits/stdc++.h> #define LL long long #define fi first #define se second #define mk make_pair #define PII pair<int, int> #define PLI pair<L…

E. Bear and Forgotten Tree 2 题目连接: http://www.codeforces.com/contest/653/problem/E Description A tree is a connected undirected graph consisting of n vertices and n  -  1 edges. Vertices are numbered 1 through n. Limak is a little polar bear. He once…

D. Delivery Bears 题目连接: http://www.codeforces.com/contest/653/problem/D Description Niwel is a little golden bear. As everyone knows, bears live in forests, but Niwel got tired of seeing all the trees so he decided to move to the city. In the city, N…

C. Bear and Up-Down 题目连接: http://www.codeforces.com/contest/653/problem/C Description The life goes up and down, just like nice sequences. Sequence t1, t2, ..., tn is called nice if the following two conditions are satisfied: ti < ti + 1 for each odd…

B. Bear and Compressing 题目连接: http://www.codeforces.com/contest/653/problem/B Description Limak is a little polar bear. Polar bears hate long strings and thus they like to compress them. You should also know that Limak is so young that he knows only…

A. Bear and Three Balls 题目连接: http://www.codeforces.com/contest/653/problem/A Description Limak is a little polar bear. He has n balls, the i-th ball has size ti. Limak wants to give one ball to each of his three friends. Giving gifts isn't easy - th…

A. Bear and Three Balls time limit per test 2 seconds memory limit per test 256 megabytes input standard input output standard output Limak is a little polar bear. He has n balls, the i-th ball has size ti. Limak wants to give one ball to each of his…

传送门 A. Bear and Three Balls time limit per test 2 seconds memory limit per test 256 megabytes input standard input output standard output Limak is a little polar bear. He has n balls, the i-th ball has size ti. Limak wants to give one ball to each of…