并查集（本题输入会超时要关闭输入流）

#include<bits/stdc++.h>

using namespace std;

const int N = 1e5 + 5;

int fa[N], rk[N];

int n, m;

void init()

{

for (int i = 1; i <= n; i++)

{

fa[i] = i;

}

}

int find(int x)

{

if (fa[x] != x)

{

return find(fa[x]);

}

return fa[x];

}

void union_(int a, int b)

{

int x = find(a); int y = find(b);

if (rk[x] > rk[y]) fa[y] = x;

else if (rk[y] > rk[x]) fa[x] = y;

else {

fa[x] = y; rk[y]++;

}

}

int main()

{

ios::sync_with_stdio(0); cin.tie(0); cout.tie(0);//关闭输入流，不然会超时

cin >> n >> m;

init();

for (int i = 1; i <= m; i++)

{

int x, y;

cin >> x >> y;

union_(x, y);

}

int T;

cin >> T;

while (T--)

{

int x, y;

cin >> x >> y;

if (find(x) == find(y))

{

cout << "Yes" << endl;

}

else

{

cout << "No" << endl;

}

}

}