二分图匹配1.最大匹配（hdu1068）Girls and BoysTime Limit: 20000/10000 MS (Java/Others) Memory Limit: 65536/32768 K (Java/Others)Total Submission(s): 6410 Accepted Submission(s): 2888Problem Descriptionthe second year of the university somebody started a study on the romantic relations between the students. The relation “romantically involved” is defined between one girl and one boy. For the study reasons it is necessary to find out the maximum set satisfying the condition: there are no two students in the set who have been “romantically involved”. The result of the program is the number of students in such a set.The input contains several data sets in text format. Each data set represents one set of subjects of the study, with the following description:the number of studentsthe description of each student, in the following formatstudent_identifier:(number_of_romantic_relations) student_identifier1 student_identifier2 student_identifier3 ...orstudent_identifier:(0)The student_identifier is an integer number between 0 and n-1, for n subjects.For each given data set, the program should write to standard output a line containing the result.Sample Input70: (3) 4 5 61: (2) 4 62: (0)3: (0)4: (2) 0 15: (1) 06: (2) 0 130: (2) 1 21: (1) 02: (1) 0Sample Output5 22.最小点覆盖（hdu1150）Machine ScheduleTime Limit: 2000/1000 MS (Java/Others) Memory Limit: 65536/32768 K (Java/Others)Total Submission(s): 4937 Accepted Submission(s): 2448Problem DescriptionAs we all know, machine scheduling is a very classical problem in computer science and has been studied for a very long history. Scheduling problems differ widely in the nature of the constraints that must be satisfied and the type of schedule desired. Here we consider a 2-machine scheduling problem.There are two machines A and B. Machine A has n kinds of working modes, which is called mode_0, mode_1, …, mode_n-1, likewise machine B has m kinds of working modes, mode_0, mode_1, … , mode_m-1. At the beginning they are both work at mode_0.For k jobs given, each of them can be processed in either one of the two machines in particular mode. For example, job 0 can either be processed in machine A at mode_3 or in machine B at mode_4, job 1 can either be processed in machine A at mode_2 or in machine B at mode_4, and so on. Thus, for job i, the constraint can be represent as a triple (i, x, y), which means it can be processed either in machine A at mode_x, or in machine B at mode_y.Obviously, to accomplish all the jobs, we need to change the machine's working mode from time to time, but unfortunately, the machine's working mode can only be changed by restarting it manually. By changing the sequence of the jobs and assigning each job to a suitable machine, please write a program to minimize the times of restarting machines.InputThe input file for this program consists of several configurations. The first line of one configuration contains three positive integers: n, m (n, m < 100) and k (k < 1000). The following klines give the constrains of the k jobs, each line is a triple: i, x, y.The input will be terminated by a line containing a single zero.OutputThe output should be one integer per line, which means the minimal times of restarting machine.Sample Input5 5 100 1 11 1 22 1 33 1 44 2 15 2 26 2 37 2 48 3 39 4 3Sample Output33.最小路径覆盖（hdu1151）Air RaidTime Limit: 2000/1000 MS (Java/Others) Memory Limit: 65536/32768 K (Java/Others)Total Submission(s): 2766 Accepted Submission(s): 1816Problem DescriptionConsider a town where all the streets are one-way and each street leads from one intersection to another. It is also known that starting from an intersection and walking through town's streets you can never reach the same intersection i.e. the town's streets form no cycles.With these assumptions your task is to write a program that finds the minimum number of paratroopers that can descend on the town and visit all the intersections of this town in such a way that more than one paratrooper visits no intersection. Each paratrooper lands at an intersection and can visit other intersections following the town streets. There are no restrictions about the starting intersection for each paratrooper.InputY our program should read sets of data. The first line of the input file contains the number of the data sets. Each data set specifies the structure of a town and has the format:no_of_intersectionsno_of_streetsS1 E1S2 E2......Sno_of_streets Eno_of_streetsThe first line of each data set contains a positive integer no_of_intersections (greater than 0 and less or equal to 120), which is the number of intersections in the town. The second line contains a positive integer no_of_streets, which is the number of streets in the town. The next no_of_streets lines, one for each street in the town, are randomly ordered and represent the town's streets. The line corresponding to street k (k <= no_of_streets) consists of two positive integers, separated by one blank: Sk (1 <= Sk <= no_of_intersections) - the number of the intersection that is the start of the street, and Ek (1 <= Ek <= no_of_intersections) - the number of the intersection that is the end of the street. Intersections are represented by integers from 1 to no_of_intersections.There are no blank lines between consecutive sets of data. Input data are correct.OutputThe result of the program is on standard output. For each input data set the program prints on a single line, starting from the beginning of the line, one integer: the minimum number of paratroopers required to visit all the intersections in the town.Sample Input2433 41 32 3331 31 22 3Sample Output214.二分图最优匹配（hdu2255）奔小康赚大钱Time Limit: 1000/1000 MS (Java/Others) Memory Limit: 32768/32768 K (Java/Others)Total Submission(s): 2582 Accepted Submission(s): 1137Problem Description传说在遥远的地方有一个非常富裕的村落,有一天,村长决定进行制度改革：重新分配房子。