1⃣️集合个数最多是n个,即每人一个集合
2⃣️通过共同爱好找到人的编号,将相同爱好的人合并,而不是合并爱好
3⃣️并查集函数包括 查找根节点(同时压缩路径),union,init,
数组包括 isroot[], father[], 如果一个结点有多个元素,例如一
个人有多个爱好,找的是相同爱好,合并的是人,需
添加course[].通过course找到和人的编号,合并人
#include <cstdio>
#include <vector>
#include <algorithm>
using namespace std;
vector<int> father, isRoot;
int cmp1(int a, int b){
return a > b;
}
int findFather(int x) {
int a = x;
while(x != father[x])
x = father[x];
while(a != father[a]) {
int z = a;
a = father[a];
father[z] = x;
}
return x;
}
void Union(int a, int b) {
int faA = findFather(a);
int faB = findFather(b);
if(faA != faB)
father[faA] = faB;
}
void init(int n){
for(int i = 1; i <= n; i++)
father[i] = i;
}
int main() {
int n, k, t, num = 0;
int course[1001] = {
0};
scanf("%d", &n);
father.resize(n + 1);
isRoot.resize(n + 1);
init(n);
for(int i = 1; i <= n; i++) {
scanf("%d:", &k);
for(int j = 0; j < k; j++) {
scanf("%d", &t);
if(course[t] == 0)
course[t] = i;
else
Union(i, findFather(course[t])); //和course[t]号是朋友
}
}
for(int i = 1; i <= n; i++)
isRoot[findFather(i)]++;
for(int i = 1; i <= n; i++) {
if(isRoot[i] != 0)
num++;
}
printf("%d\n", num);
sort(isRoot.begin(), isRoot.end(), cmp1);
for(int i = 0; i < num; i++) {
printf("%d", isRoot[i]);
if(i != num - 1) printf(" ");
}
return 0;
}