poj-1182 食物链 **

 1 // poj1182.cpp 
 2 // 与 poj-1703 Find them, Catch them 思想类似， 只是多了一种状态，rank取值为0、1、2：
 3 //    0 ： x 与 fa[x] 同类
 4 //    1 :  x 被 fa[x] 吃 
 5 //    2 ： x 吃 fa[x]
 6 
 7 #include "stdafx.h"
 8 #include <cstdio>
 9 using namespace std;
10 
11 const int maxn = 50000 + 10;
12 const int maxk = 100000 + 10;
13 
14 int n, k, d, x, y, ans = 0;
15 int fa[maxn], rank[maxn];
16 
17 void makeSet(int tot){
18     for(int i=0; i<tot; i++){
19         fa[i] = i;
20         rank[i] = 0;
21     }
22 }
23 
24 int findSet(int x){
25     if(x == fa[x])
26         return x;
27 
28     int tmp = fa[x];
29     fa[x] = findSet(fa[x]);
30     rank[x] = (rank[tmp] + rank[x]) % 3;
31 
32     return fa[x];
33 }
34 
35 void unionSet(int x, int y, int r){
36     int fx = findSet(x);
37     int fy = findSet(y);
38     if(fx == fy) return;
39 
40     int tmp = 0;
41     if(rank[x] == 1) tmp = 2;
42     else if(rank[x] == 2) tmp = 1;
43 
44     rank[fx] = (rank[y] + r + tmp) % 3;
45     fa[fx] = fy;
46 }
47 
48 bool isTrue(int x, int y, int r){
49     int fx = findSet(x);
50     int fy = findSet(y);
51 
52     if(fx != fy) return true;
53 
54     int tmp = 0;
55     if(rank[y] == 1) tmp = 2;
56     else if(rank[y] == 2) tmp = 1;
57 
58     int tmp2 = (tmp + rank[x]) % 3;
59     if(tmp2 == r) return true;
60     return false;
61 }
62 
63 
64 int _tmain(int argc, _TCHAR* argv[])
65 {
66     scanf("%d%d", &n, &k);
67 
68     //initial
69     makeSet(n);
70 
71     //input
72     for(int i=0; i<k; i++){
73         scanf("%d%d%d", &d, &x, &y);
74 
75         //case 3:
76         if(x > n || y > n) ans++;
77         //case 2:
78         else if(d == 2 && x == y) ans++;
79         //case 1:
80         else{
81             int r;
82             if(d == 1) r = 0;
83             else r = 2;
84 
85             if(!isTrue(x, y, r)) ans++;
86             else unionSet(x, y, r);
87         }
88 
89     }
90 
91     printf("%d\n", ans);
92 
93     return 0;
94 }