{"trustable":false,"prependHtml":"\u003cscript\u003e window.katexOptions \u003d { disable: true }; \u003c/script\u003e\n\u003cscript type\u003d\"text/x-mathjax-config\"\u003e\n MathJax.Hub.Config({\n tex2jax: {\n inlineMath: [[\u0027$$$\u0027,\u0027$$$\u0027], [\u0027$\u0027,\u0027$\u0027]],\n displayMath: [[\u0027$$$$$$\u0027,\u0027$$$$$$\u0027], [\u0027$$\u0027,\u0027$$\u0027]]\n }\n });\n\u003c/script\u003e\n\u003cscript async src\u003d\"https://mathjax.codeforces.org/MathJax.js?config\u003dTeX-AMS-MML_HTMLorMML\" type\u003d\"text/javascript\"\u003e\u003c/script\u003e","sections":[{"title":"","value":{"format":"HTML","content":"题目大意:\n\n一共有N个学生跟P门课程,一个学生可以任意选一 门或多门课,问是否达成: \u003cp\u003e\n 1.每个学生选的都是不同的课(即不能有两个学生选同一门课)\u003cp\u003e\n 2.每门课都有一个代表(即P门课都被成功选过)\u003cp\u003e\n输入为:\u003cp\u003e\n第一行一个T代表T组数据\u003cp\u003e\nP N(P课程数, N学生数)\u003cp\u003e\n接着P行:\u003cp\u003e\n\u003cp\u003e\n第几行代表第几门课程,首先是一个数字k代表对这门课程感兴趣的同学的个数,接下来是k个对这门课程感兴趣同学的编号。\u003cp\u003e\n输出为:\u003cp\u003e\n若能满足上面两个要求这输出”YES”,否则为”NO”\u003cp\u003e\n注意:一个学生只能担任一个课的课代表.....\u003cp\u003e\n\u003cscript type\u003d\u0027text/x-mathjax-config\u0027\u003eMathJax.Hub.Config({tex2jax: { inlineMath: [[\u0027$\u0027,\u0027$\u0027]] } }); \u003c/script\u003e\n\u003cscript type\u003d\u0027text/javascript\u0027 src\u003d\u0027https://cdnjs.cloudflare.com/ajax/libs/mathjax/2.7.1/MathJax.js?config\u003dTeX-AMS-MML_HTMLorMML\u0027\u003e\u003c/script\u003e\n\u003cscript type\u003d\u0027text/javascript\u0027\u003esetTimeout(function(){MathJax.Hub.Queue([\u0027Typeset\u0027, MathJax.Hub, \u0027left_view\u0027]);}, 2000);\u003c/script\u003e\n\u003cdiv class\u003d\"panel_content\"\u003e\n Consider a group of N students and P courses. Each student visits zero, one or more than one courses. Your task is to determine whether it is possible to form a committee of exactly P students that satisfies simultaneously the conditions: \n \u003cbr\u003e \n \u003cbr\u003e. every student in the committee represents a different course (a student can represent a course if he/she visits that course) \n \u003cbr\u003e \n \u003cbr\u003e. each course has a representative in the committee \n \u003cbr\u003e \n \u003cbr\u003eYour program should read sets of data from a text file. The first line of the input file contains the number of the data sets. Each data set is presented in the following format: \n \u003cbr\u003e \n \u003cbr\u003eP N \n \u003cbr\u003eCount1 Student1 1 Student1 2 ... Student1 Count1 \n \u003cbr\u003eCount2 Student2 1 Student2 2 ... Student2 Count2 \n \u003cbr\u003e...... \n \u003cbr\u003eCountP StudentP 1 StudentP 2 ... StudentP CountP \n \u003cbr\u003e \n \u003cbr\u003eThe first line in each data set contains two positive integers separated by one blank: P (1 \u0026lt;\u003d P \u0026lt;\u003d 100) - the number of courses and N (1 \u0026lt;\u003d N \u0026lt;\u003d 300) - the number of students. The next P lines describe in sequence of the courses . from course 1 to course P, each line describing a course. The description of course i is a line that starts with an integer Count i (0 \u0026lt;\u003d Count i \u0026lt;\u003d N) representing the number of students visiting course i. Next, after a blank, you\u0027ll find the Count i students, visiting the course, each two consecutive separated by one blank. Students are numbered with the positive integers from 1 to N. \n \u003cbr\u003e \n \u003cbr\u003eThere are no blank lines between consecutive sets of data. Input data are correct. \n \u003cbr\u003e \n \u003cbr\u003eThe result of the program is on the standard output. For each input data set the program prints on a single line \"YES\" if it is possible to form a committee and \"NO\" otherwise. There should not be any leading blanks at the start of the line. \n \u003cbr\u003e \n \u003cbr\u003eAn example of program input and output: \n\u003c/div\u003e"}},{"title":"Input","value":{"format":"HTML","content":"\u003cpre\u003e2\n3 3\n3 1 2 3\n2 1 2\n1 1\n3 3\n2 1 3\n2 1 3\n1 1\u003c/pre\u003e"}},{"title":"Output","value":{"format":"HTML","content":"\u003cpre\u003eYES\nNO \u003c/pre\u003e"}},{"title":"Sample Input","value":{"format":"HTML","content":"\u003cpre\u003e2\n3 3\n3 1 2 3\n2 1 2\n1 1\n3 3\n2 1 3\n2 1 3\n1 1\u003c/pre\u003e"}},{"title":"Sample Output","value":{"format":"HTML","content":"\u003cpre\u003eYES\nNO \u003c/pre\u003e\n\n匈牙利算法计数\u003cp\u003e\n二分图最大匹配,对课程—学生关系建立一个图,进行二分图的最大匹配,\n\u003cp\u003e\n如果最大匹配数\u003d\u003d课程数,说明能够满足要求,否则不能。"}},{"title":"","value":{"format":"HTML","content":""}}]}