POJ 1466 Girls and Boys (maximum independent set of binary graphs)

http://poj.org/problem?id=1466

Girls and Boys

Time Limit: 5000MS		Memory Limit: 10000K
Total Submissions: 11085		Accepted: 4956

Description

In the second, 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 was necessary to find out the the maximum set satisfying the condition:there was no and the students in T He set who has been "romantically involved". The result of the program was the number of students in such a set.

Input

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 students the description of each student, in the following format student_identifier: (Number_of_ro mantic_relations) Student_identifier1 student_identifier2 student_identifier3 ... or Student_identifier: (0)
The Student_identifier is a integer number between 0 and n-1 (n <=500), for n subjects.

Output

For each given data set, the program should write to standard output a line containing the result.

Sample Input

70: (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) 0

Sample Output

52

Maximum Independent set = Total number of points-maximum matches
Because the number is enlarged by twice times, the maximum number of matches should be divided by 2.

#include <stdio.h>#include<string.h>#include<math.h>#include<stdlib.h>#include<algorithm>#defineN 510#defineINF 0x3f3f3f3fusing namespacestd;intG[n][n], vis[n], used[n];intN;BOOLFind (intu) {    inti;  for(i =0; I < n; i++)    {        if(!vis[i] &&G[u][i]) {Vis[i]=1; if(!used[i] | |Find (Used[i])) {Used[i]=u; return true; }        }    }    return false;}intMain () {intI, A, B, M, ans;  while(~SCANF ("%d", &N)) {ans=0; memset (G,0,sizeof(G));  for(i =1; I <= N; i++) {scanf ("%d: (%d)", &a, &m);  while(m--) {scanf ("%d", &b); G[A][B]=1; }} memset (used,0,sizeof(used));  for(i =0; I < n; i++) {memset (Vis,0,sizeof(VIS)); if(Find (i)) ans++; } printf ("%d\n", N-ans/2); }    return 0;}

View Code

POJ 1466 Girls and Boys (maximum independent set of binary graphs)