暑假集训(2)第三弹 ----- 食物链（poj1182)

 1 #include "cstdio"
 2 
 3 int a[50001];
 4 int re[50001];
 5 int number;
 6 void abegin(int n)
 7 {
 8     for (int i=1;i<=n;i++)
 9        {
10             a[i] = i;
11             re[i] = 0;
12        }
13 }
14 int findroot(int x)
15 {
16     if(x != a[x])
17      {
18         int temp = a[x];
19         a[x] = findroot(temp);
20         re[x] = (re[x] + re[temp]) % 3;
21      }
22    return a[x];
23 }
24 void un(int b,int c,int d)
25 {
26    int x,y;
27    x = findroot(c);
28    y = findroot(d);
29    if (x == y)
30    {
31         if (b == 1 &&  re[c] != re[d])
32                  number++;
33         if (b == 2 && re[c] != (re[d] + 2) % 3)
34                  number++;
35    }
36    else
37    {
38         a[y] = x;
39         re[y] = (re[c] + b + 2 - re[d]) % 3;
40    }
41 }
42 int main()
43 {
44     int n,k;
45     int c,d,b;
46     scanf("%d%d",&n,&k);
47     number=0;
48     abegin(n);
49     while (k--)
50     {
51         scanf ("%d%d%d",&b,&c,&d);
52         if (c>n || d>n ||(b==2 && c==d))
53         {
54             number++;
55             continue;
56         }
57         un (b,c,d);
58     }
59     printf ("%d\n",number);
60     return 0;
61 }