[luoguP2024] 食物链（并查集）

 1 #include <cstdio>
 2 #include <iostream>
 3 #define N 1000001
 4 
 5 int n, k, ans;
 6 int f[N];
 7 
 8 inline int read()
 9 {
10     int x = 0, f = 1;
11     char ch = getchar();
12     for(; !isdigit(ch); ch = getchar()) if(ch == ‘-‘) f = -1;
13     for(; isdigit(ch); ch = getchar()) x = (x << 1) + (x << 3) + ch - ‘0‘;
14     return x * f;
15 }
16 
17 inline int find(int x)
18 {
19     return x == f[x] ? x : f[x] = find(f[x]);
20 }
21 
22 inline void connect(int x, int y)
23 {
24     x = find(x);
25     y = find(y);
26     if(x ^ y) f[x] = y;
27 }
28 
29 int main()
30 {
31     int i, j, x, y, z;
32     n = read();
33     k = read();
34     for(i = 1; i <= 3 * n; i++) f[i] = i;
35     for(i = 1; i <= k; i++)
36     {
37         z = read();
38         x = read();
39         y = read();
40         if(x > n || y > n)
41         {
42             ans++;
43             continue;
44         }
45         if(z == 1)
46         {
47             if(find(x + n) == find(y) || find(x + 2 * n) == find(y))
48             {
49                 ans++;
50                 continue;
51             }
52             connect(x, y);
53             connect(x + n, y + n);
54             connect(x + 2 * n, y + 2 * n);
55         }
56         else
57         {
58             if(find(x) == find(y) || find(x + 2 * n) == find(y))
59             {
60                 ans++;
61                 continue;
62             }
63             connect(x + n, y);
64             connect(y + 2 * n, x);
65             connect(y + n, x + 2 * n);
66         }
67     }
68     printf("%d\n", ans);
69     return 0;
70 }