the 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 students
the description of each student, in the following format
student_identifier:(number_of_romantic_relations) student_identifier1 student_identifier2 student_identifier3 ...
or
student_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.
An example is given in Figure 1.
Input
7
0: (3) 4 5 6
1: (2) 4 6
2: (0)
3: (0)
4: (2) 0 1
5: (1) 0
6: (2) 0 1
3
0: (2) 1 2
1: (1) 0
2: (1) 0
Output
5
2
最大独立点集：
#include<cstring> #include<iostream> #include<string> #include<cstdio> using namespace std; const int maxn = 505; int match[maxn];int used[maxn];int map[maxn][maxn];int n; int dfs(int s) { int i,temp; for(i=0;i<n;i++) { if(map[s][i] && !used[i]) { used[i] = 1; // temp = match[i]; if(match[i]==-1 || dfs(match[i])) { match[i] = s; return 1; } } } return 0; } int solve() { int i,ans= 0; memset(match,-1,sizeof(match)); for(i=0;i<n;i++) { memset(used,0,sizeof(used)); if(dfs(i)) ans++; //if(ans==n) break; } return ans; } int main() { int m,x,y,i; while(scanf("%d",&n)!=EOF) { memset(map,0,sizeof(map)); for(i=0;i<n;i++) { scanf("%d: (%d)",&x,&m); while(m--) { scanf("%d",&y); map[x][y] = 1; } } int t = solve(); printf("%d ",n-t/2); } return 0; }