hdu 3172 Virtual Friends (字符串的并查集)

一开始一直wa，因为第一个数字t也是多组输入。

然后一直超时，因为我用的是C++里面的cin，所以非常耗时,几乎比scanf慢了10倍，但是加上了一个语句后：

std::ios::sync_with_stdio(false);                //是用来禁用cin这个兼容性的特性，禁用后就相差无几了

#include <iostream>
#include <cstdio>
#include <vector>
#include <map>
#include <string>
#include <algorithm>
using namespace std;
map<string, string>fa;
map<string, int>Rank;
const int maxn = 100005;
string a[maxn];
string b[maxn];

string Find(string x){
    if (x == fa[x])
        return x;
    else
        return fa[x] = Find(fa[x]);
}

void set_union(string x, string y){
    string xx = Find(x);
    string yy = Find(y);
    //cout << "fa: " << xx << " " << yy << endl;
    if (xx == yy){
        cout << Rank[xx] << endl;
    }
    else{
        fa[yy] = xx;
        Rank[xx] += Rank[yy];
        cout << Rank[xx] << endl;
    }
    /*
    if (Rank[xx] > Rank[yy]){
        fa[yy] = xx;
        Rank[xx] += Rank[yy];
        cout << Rank[xx] << endl;
    }
    else if (Rank[xx]==Rank[yy]){
        fa[yy] = xx;
        Rank[xx]+=Rank[yy];
        cout << Rank[xx] << endl;
    }
    else{
        fa[yy] = xx;
        Rank[yy] += Rank[xx];
        cout << Rank[yy] << endl;
    }
    */
}

void init(int sum){
    for (int i = 0; i < sum; i++){
        fa[a[i]] = a[i];
        fa[b[i]] = b[i];
        Rank[a[i]] = Rank[b[i]] = 1;
    }
}

int main(){
    std::ios::sync_with_stdio(false);
    int t;
    while (cin>>t){
        while (t--){
            int n;
            cin >> n;
            for (int i = 0; i < n; i++){
                cin >> a[i];
                cin >> b[i];
            }
            init(n);
            for (int i = 0; i < n; i++){
                //cout << "#" << i << endl;
                //cout << a[i] << " " << b[i] << endl;
                set_union(a[i], b[i]);
            }
        }
    }
    //system("pause");
    return 0;
}