ACDREAM 01F（并查集）

并查集

[code]void init() {
    for (int i = 1; i <= n; i++) {
        pa[i] = i;  
    }
}

[code]int find(int x) {
    return x == pa[x] ? x : pa[x] = find(pa[x]);
}

[code]void Union(int a, int b) {
    int ra = find(a), rb = find(b);
    if (ra < rb) {
        pa[rb] = ra;
    } else {
        pa[ra] = rb;
    } 
}