Problem:
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Connected Components

Write a program which reads relations in a SNS (Social Network Service), and judges that given pairs of users are reachable each other through the network.

Input

In the first line, two integer $n$ and $m$ are given. $n$ is the number of users in the SNS and $m$ is the number of relations in the SNS. The users in the SNS are identified by IDs $0, 1, ..., n-1$.

In the following $m$ lines, the relations are given. Each relation is given by two integers $s$ and $t$ that represents $s$ and $t$ are friends (and reachable each other).

In the next line, the number of queries $q$ is given. In the following $q$ lines, $q$ queries are given respectively. Each query consists of two integers $s$ and $t$ separated by a space character.

Output

For each query, print "yes" if $t$ is reachable from $s$ through the social network, "no" otherwise.

Constraints

$2 \leq n \leq 100,000$

$0 \leq m \leq 100,000$

$1 \leq q \leq 10,000$

Sample Input

10 9
0 1
0 2
3 4
5 7
5 6
6 7
6 8
7 8
8 9
3
0 1
5 9
1 3

Sample Output

yes
yes
no

Solution in C (judge verdict: Accepted)

#include<stdio.h>
#include<stdlib.h>

#define S 100000
#define MSIZE 100

typedef struct LINK{
	int *friend;
	int i;	//number of friends.
	int group;
}Link;

Link l[S];
int d[S];
int queue[S];
int n;

void makeGroup(int s){
	int i,j,k,f;
	int qs=0, qe=0;
	queue[qe++] = s;
	while( qs < qe ){
		k = queue[qs++];
		for( i = 0; i < l[k].i; i++ ){
			f = l[k].friend[i];
			if( l[f].group == -1 ){
				queue[qe++] = f;
				l[f].group = l[k].group;
			}
		}
	}
	return;
}

void init(){
	int m, i, j;
	int x, y;
	scanf("%d %d", &n, &m);
	for( i = 0; i < n; i++ ){
		l[i].friend = (int*)malloc(MSIZE*sizeof(int));
		l[i].group = -1;
	}
	for( i = 0; i < m; i++ ){
		scanf("%d %d", &x, &y);
		if( l[x].i > 0 && l[x].i % MSIZE == 0 ){
			l[x].friend = (int*)realloc(l[x].friend, (l[x].i+MSIZE)*sizeof(int));
		}
		if( l[y].i > 0 && l[y].i % MSIZE == 0 ){
			l[y].friend = (int*)realloc(l[y].friend, (l[y].i+MSIZE)*sizeof(int));
		}
		l[x].friend[l[x].i] = y;
		l[y].friend[l[y].i] = x;
		l[x].i++;
		l[y].i++;
	}
	//make group.
	int temp = 0;
	for( i = 0; i < n; i++ ){
		if( l[i].group != -1 ){ continue; }
		l[i].group = temp++;
		makeGroup(i);
	}
	return;
}

void isFriend(){
	int s, t;
	scanf("%d %d", &s, &t);
	printf("%s\n", (l[s].group==l[t].group?"yes":"no"));
	return;
}

int main(){
	int i, q;
	init();
	scanf("%d", &q);
	for( i = 0; i < q; i++ ){ isFriend(); }
	return 0;
}