hdu 1878 欧拉回路+并查集

 1 #include<iostream>
 2 #include<algorithm>
 3 #include<cmath>
 4 #include<vector>
 5 
 6 using namespace std;
 7 
 8 int n,m;
 9 const int MAX_N=10005;
10 int pre[MAX_N];
11 int iin[MAX_N];
12 
13 void init()
14 {
15     for(int i = 0; i <= n; i++)
16     {
17         pre[i]=i;
18         iin[i]=0;
19     }
20 }
21 
22 int find_root(int x)
23 {
24     int r = x;
25     while(r!=pre[r])
26         r = pre[r];
27     
28     int i = x,j;
29     while(i!=r)
30     {
31         j = pre[i];
32         pre[i] = r;
33         i = j;
34     }
35     return r;
36 }
37 void join(int x,int y)
38 {
39     int xx = find_root(x);
40     int yy = find_root(y);
41     if(xx!=yy)
42         pre[xx]=yy;
43 }
44 int main()
45 {
46     while(cin>>n>>m,n)
47     {
48         int a,b;
49         init();
50         for(int i = 1; i <= m; i++)
51         {
52             cin>>a>>b;
53             iin[a]++;
54             iin[b]++;
55             join(a,b);
56         }
57         int temp = find_root(1);
58         int flag = 1;
59         for(int i = 1; i <= n; i++)
60         {
61             if(iin[i]%2 || find_root(i)!=temp)
62             {
63                 flag = 0;
64                 break;
65             }
66         }
67         if(flag)
68             cout<<1<<endl;
69         else
70             cout<<0<<endl;
71     }
72     return 0;
73 }