[hdu1272]并查集

思路：裸并查集模板啊。。

#include <iostream>
#include <cstdio>
#include <algorithm>
#include <cstdlib>
#include <cstring>
#include <map>
#include <queue>
#include <deque>
#include <cmath>
#include <vector>
#include <ctime>
#include <cctype>
#include <set>

using namespace std;

#define mem0(a) memset(a, 0, sizeof(a))
#define lson l, m, rt << 1
#define rson m + 1, r, rt << 1 | 1
#define define_m int m = (l + r) >> 1
#define Rep(a, b) for(int a = 0; a < b; a++)
#define lowbit(x) ((x) & (-(x)))
#define constructInt4(name, a, b, c, d) name(int a = 0, int b = 0, int c = 0, int d = 0): a(a), b(b), c(c), d(d) {}
#define constructInt3(name, a, b, c) name(int a = 0, int b = 0, int c = 0): a(a), b(b), c(c) {}
#define constructInt2(name, a, b) name(int a = 0, int b = 0): a(a), b(b) {}

typedef double db;
typedef long long LL;
typedef pair<int, int> pii;
typedef multiset<int> msi;
typedef multiset<int>::iterator msii;
typedef set<int> si;
typedef set<int>::iterator sii;
typedef vector<int> vi;

const int dx[8] = {1, 0, -1, 0, 1, 1, -1, -1};
const int dy[8] = {0, -1, 0, 1, -1, 1, 1, -1};
const int maxn = 1e5 + 7;
const int maxm = 1e5 + 7;
const int maxv = 1e7 + 7;
const int MD = 1e9 +7;
const int INF = 1e9 + 7;
const double PI = acos(-1.0);
const double eps = 1e-10;

struct UnionFindSets {
    vi f;
    int N;
    UnionFindSets() { f.clear(); }
    void clear() { f.clear(); }
    void resize(int n) { N = n + 2; f.resize(n + 5); }
    void Init() { for (int i = 1; i <= N; i++) f[i] = i; }
    int get(int u) { if (u == f[u]) return u; return f[u] = get(f[u]); }
    void add(int u, int v) { f[get(u)] = get(v); }
    bool find(int u, int v) { return get(u) == get(v); }
};

UnionFindSets ufs;

bool mark[100007];

int main() {
    //freopen("in.txt", "r", stdin);
    ufs.resize(1e5 + 7);
    ufs.Init();
    int v = 0, a, b, yes = 1;
    while (1) {
        scanf("%d%d", &a, &b);
        if (!v) v = a;
        mark[a] = mark[b] = 1;
        if (a == -1 && b == -1) break;
        if (a == 0 && b == 0) {
            for (int i = 1; i <= 1e5; i++) {
                if (mark[i] && ufs.get(i) != ufs.get(v)) {
                    yes = 0;
                    break;
                }
            }
            if (yes) puts("Yes");
            else puts("No");
            ufs.Init();
            mem0(mark);
            v = 0;
            yes = 1;
            continue;
        }
        if (ufs.find(a, b)) {
            yes = 0;
        }
        ufs.add(a, b);
    }
    return 0;
}