51nod-1515 明辨是非——并查集

 1 #include <iostream>
 2 #include <cstdio>
 3 #include <set>
 4 #include <map>
 5 
 6 using namespace std;
 7 
 8 const int MAXN = 2e5 + 5;
 9 
10 int n, cnt = 1,f[MAXN];
11 set<int> nt[MAXN];
12 map<int, int> eq;
13 
14 int find(int x)
15 {
16     return f[x] == x ? x : f[x] = find(f[x]);
17 }
18 
19 int main()
20 {
21     //freopen("in.txt","r",stdin);
22     cin>>n;
23     n +=5;
24     for (int i = 1; i <= n; i++)
25     {
26         f[i] = i;
27     }
28     n -=5;
29     
30     int x, y, p;
31     while (n--)
32     {
33         cin>>x>>y>>p;
34         if (eq[x])//计数标号 
35         {
36             x = eq[x];
37         }
38         else
39         {
40             ++cnt;
41             eq[x]=cnt;
42             x=cnt;
43         }
44         if (eq[y])
45         {
46             y = eq[y];
47         }
48         else
49         {
50             ++cnt;
51             eq[y]=cnt;
52             y=cnt;
53         }
54         int u = find(x), v = find(y);
55         if (p == 1)//限制相等 
56         {
57             if (nt[u].count(v)) //限制不相等
58             {
59                 cout<<"NO"<<endl;
60             }
61             else if (u != v)    //未限制但并未相等
62             {
63                 if (nt[u].size() > nt[v].size())
64                 {
65                     swap(u, v);
66                 }
67                 f[u] = v;
68                 set<int>::iterator it;
69                 for (it = nt[u].begin(); it != nt[u].end(); it++)
70                 {
71                     nt[*it].insert(v);
72                     nt[v].insert(*it);
73                 }
74                 cout<<"YES"<<endl;
75             }
76             else
77             {
78                 cout<<"YES"<<endl;
79             }
80         }
81         else//限制不相等 
82         {
83             if (u == v)
84             {
85                 cout<<"NO"<<endl;
86             }
87             else
88             {
89                 nt[u].insert(v);
90                 nt[v].insert(u);
91                 cout<<"YES"<<endl;
92             }
93         }
94     }
95 
96     return 0;
97 }