PAT1107:Social Clusters
1107. Social Clusters (30)
When register on a social network, you are always asked to specify your hobbies in order to find some potential friends with the same hobbies. A "social cluster" is a set of people who have some of their hobbies in common. You are supposed to find all the clusters.
Input Specification:
Each input file contains one test case. For each test case, the first line contains a positive integer N (<=1000), the total number of people in a social network. Hence the people are numbered from 1 to N. Then N lines follow, each gives the hobby list of a person in the format:
Ki: hi[1] hi[2] ... hi[Ki]
where Ki (>0) is the number of hobbies, and hi[j] is the index of the j-th hobby, which is an integer in [1, 1000].
Output Specification:
For each case, print in one line the total number of clusters in the network. Then in the second line, print the numbers of people in the clusters in non-increasing order. The numbers must be separated by exactly one space, and there must be no extra space at the end of the line.
Sample Input:8 3: 2 7 10 1: 4 2: 5 3 1: 4 1: 3 1: 4 4: 6 8 1 5 1: 4Sample Output:
3 4 3 1
思路
并查集问题,course数组保存最先选择该课程的,source保存每个人关联的源点,然后查找合并就行。
代码
#include<iostream> #include<vector> #include<algorithm> #include<iomanip> using namespace std; vector<int> source(1001,0); vector<int> course(1001,0); int findSource(int a) { int t = a; while(source[a] != a) { a = source[a]; } while(source[t] != t) { int tmp = t; t = source[t]; source[tmp] = a; } return a; } void Union(int a,int b) { a = findSource(a); b = findSource(b); if( a != b) source[a] = b; } bool cmp(int a,int b) { return a > b; } int main() { int N; while(cin >> N) { vector<int> root(N + 1,0); for(int i = 1;i <= N;i++) { source[i] = i; } for(int i = 1;i <= N;i++) { int k; scanf("%d : ",&k); for(int j = 1;j <= k;j++) { int h; cin >> h; if(course[h] == 0) course[h] = i; Union(i,findSource(course[h])); } } for(int i = 1;i <= N;i++) { ++root[findSource(i)]; } int cnt = 0; for(int i = 1;i <= N;i++) { if(root[i] > 0) cnt++; } cout << cnt << endl; int flag = 0; sort(root.begin(),root.end(),cmp); for(int i = 0;i < cnt;i++) { if(flag++ != 0) cout << " "; cout << root[i]; } } }