Go: package main

import (
	"fmt"
	"bufio"
	"os"
	"strconv"
)

func main() {
	var n,m int
	fmt.Scan(&n)
	group := make([]int, n)
	for i := 0; i < n; i++ {
		group[i] = i
	}
	
	fmt.Scan(&m)
	sc := bufio.NewScanner(os.Stdin)
	sc.Split(bufio.ScanWords)
	for i := 0; i < m; i++ {
		sc.Scan()
		s, _ := strconv.Atoi(sc.Text())
		sc.Scan()
		t, _ := strconv.Atoi(sc.Text())

		if group[s] < group[t] {
			group[t] = group[s]
		} else {
			group[s] = group[t]
		}
	}

	sc.Scan()
	q, _ := strconv.Atoi(sc.Text())
	for i := 0; i < q; i++ {
		sc.Scan()
		s, _ := strconv.Atoi(sc.Text())
		sc.Scan()
		t, _ := strconv.Atoi(sc.Text())

		if root(s, &group) == root(t, &group) {
			fmt.Println("yes")
		} else {
			fmt.Println("no")
		}
	}
}

func root(i int, group *[]int) int {
	if i == (*group)[i] {
		return i
	}
	(*group)[i] = root((*group)[i], group)
	return (*group)[i]
}

C++: #include <stdio.h>
#include <string.h>
#define N 100010
int father[N], root[N];
int findfather(int x){
    if(root[x]) return father[x];
    else return findfather(father[x]);
}
int main(){
    int n, m;
    scanf("%d %d", &n, &m);
    for(int i = 0; i < n; i++) {
        father[i] = i; root[i] = 1;
    }
    for(int k = 0; k < m; k++){
        int a, b;
        scanf("%d %d", &a, &b);
        root[b] = 0;
        father[b] = findfather(a);
    }
    int q;
    scanf("%d", &q);
    while(q--){
        int x, y;
        scanf("%d %d", &x, &y);
        if(father[x] == father[y]) printf("yes\n");
        else printf("no\n");
    }
    return 0;
}