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1154 - PenguinsPDF (English)StatisticsForumTime Limit: 4 second(s)Memory Limit: 32 MBSomewhere near the South Pole, a number of penguins are standing on

Ombrophobic BovinesTime Limit: 1000MS Memory Limit: 65536KTotal Submissions: 16460 Accepted: 3593DescriptionFJ's cows really hate getting wet so much that the m

Minimum CostTime Limit: 4000MS Memory Limit: 65536KTotal Submissions: 15041 Accepted: 5169DescriptionDearboy, a goods victualer, now comes to a big problem, and

Power NetworkTime Limit: 2000MS Memory Limit: 32768KTotal Submissions: 25108 Accepted: 13077DescriptionA power network consists of nodes (power stations, consum

Farm TourTime Limit: 1000MS Memory Limit: 65536KTotal Submissions: 13514 Accepted: 5128DescriptionWhen FJ's friends visit him on the farm, he likes to show them

PIGSTime Limit: 1000MS Memory Limit: 10000KTotal Submissions: 18123 Accepted: 8246DescriptionMirko works on a pig farm that consists of M locked pig-houses and

A Plug for UNIXTime Limit: 1000MS Memory Limit: 65536KTotal Submissions: 14711 Accepted: 4959DescriptionYou are in charge of setting up the press room for the i

Optimal MilkingTime Limit: 2000MS Memory Limit: 30000KTotal Submissions: 13897 Accepted: 5018Case Time Limit: 1000MSDescriptionFJ has moved his K (1 <= K

DiningTime Limit: 2000MS Memory Limit: 65536KTotal Submissions: 11097 Accepted: 5096DescriptionCows are such finicky eaters. Each cow has a preference for certa

Task ScheduleTime Limit: 2000/1000 MS (Java/Others)    Memory Limit: 65536/32768 K (Java/Others)Total Submission(s): 5398    Accepted Submission(s): 1742Problem DescriptionOur geometry pri

MissileTime Limit: 2 Seconds      Memory Limit: 65536 KB You control N missile launching towers. Every tower has enough missiles, but for each tower only one missile can be launch at the s

Dual Core CPUTime Limit: 15000MS Memory Limit: 131072KTotal Submissions: 20852 Accepted: 9010Case Time Limit: 5000MSDescriptionAs more and more computers

1155 - Power TransmissionPDF (English)StatisticsForumTime Limit: 2 second(s)Memory Limit: 32 MBDESA is taking a new project to transfer power. Power is

1153 - Internet BandwidthPDF (English)StatisticsForumTime Limit: 2 second(s)Memory Limit: 32 MBOn the Internet, machines (nodes) are richly interconnect

Cable TV NetworkTime Limit: 1000MS Memory Limit: 30000KTotal Submissions: 4276 Accepted: 2008DescriptionThe interconnection of the relays in a cable TV network is

题意：有N个人、F种食物和D种饮料，已经给出每种食物、饮料的数目。输入下面有N*F和N*D两个矩阵，N*F矩阵的第i行第j列表示第i个人是否喜欢第j种食物，若该位置的元素为Y表示喜欢否则不喜欢。N*D矩阵的第i行第j列表示第i个人是否喜欢第j种饮料，若该位置的元素为Y表示喜欢否则不喜欢。每个人的需求是——选择一份食物和一份饮料(必须是他们喜欢的)，问最多可以满足几个人的需求。解析：比较常规的最大流问题，见图比较好想，要注意的是要拆点见图，对人拆点，把每个人拆成两个点，为左点和右点，两点之间容

题意：给出一个又n个点，m条边组成的无向图。给出两个点s，t。对于图中的每个点，去掉这个点都需要一定的花费。求至少多少花费才能使得s和t之间不连通。见图思路：1，把每个点i拆成左点i ->右点i+N的一条边，边权为去掉i点的费用；2，源点向s左点建边，边权为无穷大，表示不能去掉该边；3，d右点向汇点建边，边权为无穷大；4，对于无向边<u, v>，建双边<u右，v左>和<v右，u左>，边权为无穷大，表示不能去掉该边。最后源点到汇点跑一次最大流即求出最小割。

题意：给你N个点、M条无向边以及边的权值，又给你源点A和汇点B。问你A到B的最小割是否唯一解析：1、我们先对原图求一次最大流2、对残留网络，我们从S开始，找到所有所有S能到达的点；再从T开始，找出所有能到达T的点。3、判断原网络中是否还有没有访问到的点，如果没有，则唯一，否者，不唯一！

题意：有N个城市以及连接这些城市的M条无向边，其中城市1是啤酒产地。给出N-1个数字，分别表示每个城市里啤酒每桶的价格（城市1不算），我们可以认为这N-1个城市对啤酒的需求是没有限制的即 无限大。已知每条无向边最多可以运送啤酒的桶数 和运送每桶的花销，问你从城市1出发卖啤酒可以得到的最大收益。解析：算是比较好像的费用流了，但要注意。每次SPFA找到可以从源点到汇点的最长路后，我

题意：有N个学生（编号0到N-1）和M个房间（编号0到M-1）。给你E条如(a, b, c)的关系表示学生a对房间b评价为c，当c现在问你存不存在一种方案 保证任意一个学生都不能选上他不喜欢的房间，若存在则输出满足条件的最大评价值之和，若不存在输出-1。解析：费用法流的常规题，思路很好想，1A么么哒。简单说一下见图步骤：（1）超级源点到每个学生建边， 容量为1， 费用为

Tricks DeviceTime Limit: 2000/1000 MS (Java/Others)    Memory Limit: 65536/65536 K (Java/Others)Total Submission(s): 2208    Accepted Submission(s): 584Problem DescriptionInnocent Wu follo

Pahom on WaterTime Limit: 2000/1000 MS (Java/Others)    Memory Limit: 32768/32768 K (Java/Others)Total Submission(s): 658    Accepted Submission(s): 302Problem DescriptionPahom on Water is

Flow ProblemTime Limit: 5000/5000 MS (Java/Others)    Memory Limit: 65535/32768 K (Java/Others)Total Submission(s): 10338    Accepted Submission(s): 4871Problem DescriptionNetwork flow is

Cyclic TourTime Limit: 1000/1000 MS (Java/Others)    Memory Limit: 32768/65535 K (Java/Others)Total Submission(s): 1950    Accepted Submission(s): 984Problem DescriptionThere are N cities

Jamie's Contact GroupsTime Limit: 7000MS Memory Limit: 65536KTotal Submissions: 6902 Accepted: 2261DescriptionJamie is a very popular girl and has quite a lot o

Gold TransportationTime Limit: 2000MS Memory Limit: 65536KTotal Submissions: 3079 Accepted: 1101DescriptionRecently, a number of gold mines have been discovered

Secret Milking MachineTime Limit: 1000MS Memory Limit: 65536KTotal Submissions: 10625 Accepted: 3111DescriptionFarmer John is constructing a new milking machine

How Many Shortest PathTime Limit: 10 Seconds      Memory Limit: 32768 KB Given a weighted directed graph, we define the shortest path as the path who has the smallest length among all the

Route RedundancyTime Limit: 2000/1000 MS (Java/Others)    Memory Limit: 32768/32768 K (Java/Others)Total Submission(s): 516    Accepted Submission(s): 294Problem DescriptionA city is made

Destroying The GraphTime Limit: 2000MS Memory Limit: 65536KTotal Submissions: 7597 Accepted: 2434 Special JudgeDescriptionAlice and Bob play the following g

ParatroopersTime Limit: 1000MS Memory Limit: 65536KTotal Submissions: 7847 Accepted: 2365DescriptionIt is year 2500 A.D. and there is a terrible war between the f

Flow ProblemTime Limit: 5000/5000 MS (Java/Others)    Memory Limit: 65535/32768 K (Java/Others)Total Submission(s): 9074    Accepted Submission(s): 4265Problem DescriptionNetwork flow is a

Going HomeTime Limit: 10000/5000 MS (Java/Others)    Memory Limit: 65536/32768 K (Java/Others)Total Submission(s): 3452    Accepted Submission(s): 1771Problem DescriptionOn a grid map ther

TourTime Limit: 3000/1000 MS (Java/Others)    Memory Limit: 65535/65535 K (Java/Others)Total Submission(s): 2308    Accepted Submission(s): 1156Problem DescriptionIn the kingdom of Henryy,

Alice's ChanceTime Limit: 1000MS Memory Limit: 10000KTotal Submissions: 6384 Accepted: 2607DescriptionAlice, a charming girl, have been dreaming of being a movi

Matrix AgainTime Limit: 5000/2000 MS (Java/Others)    Memory Limit: 102400/102400 K (Java/Others)Total Submission(s): 3457    Accepted Submission(s): 1020Problem DescriptionStarvae very li

MatrixTime Limit: 2000/1000 MS (Java/Others)    Memory Limit: 32768/32768 K (Java/Others)Total Submission(s): 2062    Accepted Submission(s): 1074Problem DescriptionYifenfei very like play

Drainage DitchesTime Limit: 1000MS Memory Limit: 10000KTotal Submissions: 62111 Accepted: 23859DescriptionEvery time it rains on Farmer John's fields, a pond fo

TransportationTime Limit: 2000/1000 MS (Java/Others)    Memory Limit: 32768/32768 K (Java/Others)Total Submission(s): 2441    Accepted Submission(s): 1041Problem DescriptionThere are N cit

The Exchange of ItemsTime Limit: 2 Seconds      Memory Limit: 65536 KB Bob lives in an ancient village, where transactions are done by one item exchange with another. Bob is very clever an