7-8 File Transfer (25 分)

并查集入门题
注意：
最后遍历根的时候还要find一次

#include 
#include 
#include 
#include 
using namespace std;
const int N = 1e4+7;
int root[N];
int find(int x){
	if(x == root[x]) return x;
	else return root[x] = find(root[x]);
}
int main(){
	int n, u, v;
	cin>>n;
	char c;
	for(int i = 0; i <= n; i++){
		root[i] = i;
	}
	getchar();
	while(cin>>c){
		if(c == 'S') break;
		cin>> u>> v;
		int a = find(u);
		int b = find(v);
		if(c == 'I'){
			if(a != b){
				root[b] = a;
			}
		}else{
			if(a == b) cout<<"yes"<<endl;
			else cout<<"no"<<endl;	
		}
	}
	unordered_set<int> st;
	for(int i = 1; i <= n; i++){
		st.insert(find(i));
	}
	if(st.size() == 1) cout<<"The network is connected."<<endl;
	else cout<<"There are "<<st.size()<<" components."<<endl;
	return 0;
}