pku 1182 食物链
种类并查集的经典题目，和NOIP2010里的关押罪犯一个类型，0，1，2表示三个种类，在合并时用类似向量的方法去导公式，其他的模拟操作即可。
View Code
1 program pku1182(input,output);
2 var
3 father,r : array[0..50000] of longint;
4 i,n,x,y,answer,k,t : longint;
5 function find(i : longint):longint;
6 var
7 temp:longint;
8 begin
9 if father[i]=i then
10 exit(i);
11 temp:=father[i];
12 father[i]:=find(father[i]);
13 r[i]:=(r[temp]+r[i]) mod 3;
14 exit(father[i]);
15 end;
16 procedure union(x,y,h:longint);
17 var
18 a,b:longint;
19 begin
20 a:=find(x);
21 b:=find(y);
22 father[a]:=b;
23 r[a]:=(r[y]+h-r[x]+3) mod 3;
24 end;
25 begin
26 answer:=0;
27 readln(n,k);
28 for i:=1 to n do
29 father[i]:=i;
30 for i:=1 to k do
31 begin
32 readln(t,x,y);
33 if (x>n)or(y>n) then
34 begin
35 inc(answer);
36 continue;
37 end;
38 case t of
39 1:if find(x)=find(y) then
40 begin
41 if r[x]<>r[y] then
42 inc(answer)
43 end
44 else
45 union(x,y,0);
46 2:begin
47 if x=y then
48 begin
49 inc(answer);
50 continue;
51 end;
52 if find(x)=find(y) then
53 begin
54 if r[x]<>(r[y]+1) mod 3 then
55 inc(answer)
56 end
57 else
58 union(x,y,1);
59 end;
60 end;
61 end;
62 writeln(answer);
63 end.
