POJ1182食物链【并查集+根节点的偏移】

 1 #include <iostream>
 2 #include <cstdio>
 3 #include <cstring>
 4 using namespace std;
 5 
 6 const int maxn = 50005;
 7 
 8 int fa[maxn], num[maxn];
 9 
10 void init(int n) {
11     for(int i = 0; i <= n; i++) {
12         fa[i] = i;
13         num[i] = 0;
14     }
15 }
16 
17 int find(int i) {
18     if(fa[i] == i) {
19         return i;
20     }
21     int fi = fa[i];
22     fa[i] = find(fa[i]);
23     num[i] = (num[i] + num[fi] + 6) % 3;
24     return fa[i];
25 }
26 
27 void unin(int u, int v) {
28     int fu = find(u); int fv = find(v);
29     if(fu != fv) {
30         fa[fv] = fu;
31         num[fv] = (num[fv] + (num[u] + 1 - num[v]) + 6) % 3;
32     }
33 }
34 
35 void unin2(int u, int v) {
36     int fu = find(u); int fv = find(v);
37     if(fu != fv) {
38         fa[fv] = fu;
39         num[fv] = (num[fv] + (num[u] - num[v]) + 6) % 3;
40     }
41 }
42 
43 int main() {
44     int n, k;
45     int c, a, b;
46     scanf("%d %d",&n, &k);
47     int ans = 0;
48     init(n);
49     while(k--) {
50         scanf("%d %d %d",&c, &a, &b);
51 
52         if(a > n || b > n) {
53             ans++;
54             continue;
55         } 
56         if(c == 2 && a == b) {
57             ans++;
58             continue;
59         }
60         if(c == 1) {
61             if(find(a) == find(b) ) {
62                 if(num[a] != num[b]) {
63                     ans++;
64                 }
65             } else {
66                 unin2(a, b);
67             }
68         } else {
69             if(find(a) == find(b) ) {
70                 if(num[b] !=  ( num[a] + 1 ) % 3 ) {
71                     ans++;
72                 }
73             } else {
74                 unin(a, b);
75             }
76         }
77     }
78     printf("%d\n", ans);
79     return 0;
80 }