Problem Description A coding contest will be held in this university, in a huge playground. The whole playground would be divided into N blocks, and there would be M directed paths linking these blocks. The i-th path goes from the u_i-th block to the…

Coding Contest Time Limit: 2000/1000 MS (Java/Others)    Memory Limit: 65536/65536 K (Java/Others)Total Submission(s): 1751    Accepted Submission(s): 374 Problem Description A coding contest will be held in this university, in a huge playground. The…

Problem DescriptionA coding contest will be held in this university, in a huge playground. The whole playground would be divided into N blocks, and there would be M directed paths linking these blocks. The i-th path goes from the ui-th block to the v…

题目链接:http://acm.hdu.edu.cn/showproblem.php?pid=5988 题目大意: 给定n个点,m条有向边,每个点是一个吃饭的地方,每个人一盒饭.每个点有S个人,有B盒饭.每条边只能被走c次,每条边上都有电线,第一个人通过的时候,不会破坏电线,从第二个人开始,每次都有概率p破坏掉电线.使得每个人都能吃饭,求最小破坏电线的概率. 解题思路: 题目要求我们求最小破坏电线的概率,就是一个最小乘积问题,加上log可以将其转变为加法,那样就可以使用费用刘来解决了. 按以下方…

http://acm.split.hdu.edu.cn/showproblem.php?pid=5988 题意:在acm比赛的时候有多个桌子,桌子与桌子之间都有线路相连,每个桌子上会有一些人和一些食物,现在要吃午饭了,有些人就可能需要到别的桌子去拿食物,但是必须沿着线路走,每根线路第一个人走时没事,接下来的人走时会有一定概率使网络瘫痪,并且每根线路最多可以走c人.现在问使网络瘫痪的最低概率是多少? 思路:建立费用流,由于概率是要相乘,这里可以转换成log后进行计算,最后再转换回来即可. 由于这题…

很巧妙的建边方式 题意:有n个区域,每个区域有一些人数si和食物bi,区域之间有m条定向路径,每条路径有人数通过上限ci.路径之间铺了电线,每当有人通过路径时有pi的概率会触碰到电线,但是第一个通过的人一定不会触碰到电线.求每个人都通过路径获取到食物后触碰到电线的最小概率. 解法:不碰到电线的概率比较好求,然后对于一条路线上的不碰到电线的概率是(1-p1)*(1-p2)...,最小费用流是没法跑乘法的,所以我们建边的费用变成log(1-p),那么乘法就变成了加法,然后要求最小值,由于log(1-…

Coding Contest http://acm.hdu.edu.cn/showproblem.php?pid=5988 Time Limit: 2000/1000 MS (Java/Others)    Memory Limit: 65536/65536 K (Java/Others)Total Submission(s): 5337    Accepted Submission(s): 1256 Problem Description A coding contest will be he…

题目链接:https://www.nowcoder.com/acm/contest/207/G 题目链接:http://acm.hdu.edu.cn/showproblem.php?pid=5988 时间限制:C/C++ 2秒,其他语言4秒空间限制:C/C++ 262144K,其他语言524288K64bit IO Format: %lld题目描述 A coding contest will be held in this university, in a huge playground. Th…

题目链接: Coding Contest Time Limit: 2000/1000 MS (Java/Others)     Memory Limit: 65536/65536 K (Java/Others) Problem Description A coding contest will be held in this university, in a huge playground. The whole playground would be divided into N blocks,…

Coding Contest Time Limit: 2000/1000 MS (Java/Others)    Memory Limit: 65536/65536 K (Java/Others)Total Submission(s): 5968    Accepted Submission(s): 1413 Problem Description A coding contest will be held in this university, in a huge playground. Th…