并查集

#define MAX 10000
int set[MAX];
int rank[MAX];

// Initialize
void init(){for (int i = 0; i < MAX; ++i) set[i] = i;}

// Find
int findSet(int v){
	if (set[v] != v) set[v] = findSet(set[v]);
	return set[v];
}

// Union by Rank
bool joinSet(int x, int y){
	int fx = findSet(x), fy = findSet(y);
	if (fx == fy) return true;
	if (rank[fx] > rank[fy]) set[fy] = fx;
	else{
		set[fx] = fy;
		if (rank[fx] == rank[fy]) ++rank[fy];
		return false;
	}
}