[hdu1272]并查集

 1 #include <iostream>
 2 #include <cstdio>
 3 #include <algorithm>
 4 #include <cstdlib>
 5 #include <cstring>
 6 #include <map>
 7 #include <queue>
 8 #include <deque>
 9 #include <cmath>
10 #include <vector>
11 #include <ctime>
12 #include <cctype>
13 #include <set>
14 
15 using namespace std;
16 
17 #define mem0(a) memset(a, 0, sizeof(a))
18 #define lson l, m, rt << 1
19 #define rson m + 1, r, rt << 1 | 1
20 #define define_m int m = (l + r) >> 1
21 #define Rep(a, b) for(int a = 0; a < b; a++)
22 #define lowbit(x) ((x) & (-(x)))
23 #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) {}
24 #define constructInt3(name, a, b, c) name(int a = 0, int b = 0, int c = 0): a(a), b(b), c(c) {}
25 #define constructInt2(name, a, b) name(int a = 0, int b = 0): a(a), b(b) {}
26 
27 typedef double db;
28 typedef long long LL;
29 typedef pair<int, int> pii;
30 typedef multiset<int> msi;
31 typedef multiset<int>::iterator msii;
32 typedef set<int> si;
33 typedef set<int>::iterator sii;
34 typedef vector<int> vi;
35 
36 const int dx[8] = {1, 0, -1, 0, 1, 1, -1, -1};
37 const int dy[8] = {0, -1, 0, 1, -1, 1, 1, -1};
38 const int maxn = 1e5 + 7;
39 const int maxm = 1e5 + 7;
40 const int maxv = 1e7 + 7;
41 const int MD = 1e9 +7;
42 const int INF = 1e9 + 7;
43 const double PI = acos(-1.0);
44 const double eps = 1e-10;
45 
46 struct UnionFindSets {
47     vi f;
48     int N;
49     UnionFindSets() { f.clear(); }
50     void clear() { f.clear(); }
51     void resize(int n) { N = n + 2; f.resize(n + 5); }
52     void Init() { for (int i = 1; i <= N; i++) f[i] = i; }
53     int get(int u) { if (u == f[u]) return u; return f[u] = get(f[u]); }
54     void add(int u, int v) { f[get(u)] = get(v); }
55     bool find(int u, int v) { return get(u) == get(v); }
56 };
57 
58 UnionFindSets ufs;
59 
60 bool mark[100007];
61 
62 int main() {
63     //freopen("in.txt", "r", stdin);
64     ufs.resize(1e5 + 7);
65     ufs.Init();
66     int v = 0, a, b, yes = 1;
67     while (1) {
68         scanf("%d%d", &a, &b);
69         if (!v) v = a;
70         mark[a] = mark[b] = 1;
71         if (a == -1 && b == -1) break;
72         if (a == 0 && b == 0) {
73             for (int i = 1; i <= 1e5; i++) {
74                 if (mark[i] && ufs.get(i) != ufs.get(v)) {
75                     yes = 0;
76                     break;
77                 }
78             }
79             if (yes) puts("Yes");
80             else puts("No");
81             ufs.Init();
82             mem0(mark);
83             v = 0;
84             yes = 1;
85             continue;
86         }
87         if (ufs.find(a, b)) {
88             yes = 0;
89         }
90         ufs.add(a, b);
91     }
92     return 0;
93 }