1118. Birds in Forest (25) 并查集

题目地址

和1107,1114题类似。

//// Created by aleafall on 16-9-28.//#include <iostream>#include <set>using namespace std;const int maxn = 10005;int father[maxn];int findFather(int x) {    if (father[x] == x) return x;    else {        int F = findFather(father[x]);        father[x] = F;        return F;    }}void Union(int a, int b) {    int faA = findFather(a);    int faB = findFather(b);    if (faA != faB) father[faA] = faB;}int main() {    for (int i = 0; i < maxn; ++i) {        father[i] = i;    }    int n, k, index, b = 0;    int q, b1, b2;    set<int> st;    cin >> n;    for (int i = 0; i < n; ++i) {        cin >> k;        int temp = 0;        for (int j = 0; j < k; ++j) {            cin >> index;            if (index > b) b = index;            if (j == 0) temp = index;            else Union(temp, index);        }    }    for (int i = 1; i <= b; ++i) {        st.insert(findFather(i));    }    cout << st.size() << " " << b << endl;    cin >> q;    for (int i = 0; i < q; ++i) {        cin >> b1 >> b2;        if (father[b1] == father[b2])            cout << "Yes\n";        else cout << "No\n";    }    return 0;}