POJ——T 1988 Cube Stacking || HDU ——T 2818 Building Block

http://poj.org/problem?id=1988

Description

Farmer John and Betsy are playing a game with N (1 <= N <= 30,000)identical cubes labeled 1 through N. They start with N stacks, each containing a single cube. Farmer John asks Betsy to perform P (1<= P <= 100,000) operation. There are two types of operations: 
moves and counts. 
* In a move operation, Farmer John asks Bessie to move the stack containing cube X on top of the stack containing cube Y. 
* In a count operation, Farmer John asks Bessie to count the number of cubes on the stack with cube X that are under the cube X and report that value.

Write a program that can verify the results of the game.

Input

* Line 1: A single integer, P

* Lines 2..P+1: Each of these lines describes a legal operation. Line 2 describes the first operation, etc. Each line begins with a ‘M‘ for a move operation or a ‘C‘ for a count operation. For move operations, the line also contains two integers: X and Y.For count operations, the line also contains a single integer: X.

Note that the value for N does not appear in the input file. No move operation will request a move a stack onto itself.

Output

Print the output from each of the count operations in the same order as the input file.

Sample Input

6
M 1 6
C 1
M 2 4
M 2 6
C 3
C 4

Sample Output

1
0
2

Source

USACO 2004 U S Open

查询x时，先维护x下边的、

 1 #include <algorithm>
 2 #include <cstdio>
 3
 4 using namespace std;
 5
 6 const int N(30005);
 7 int fa[N],sum[N],beh[N];
 8
 9 int find(int x)
10 {
11     if(fa[x]==x) return x;
12     int dad=find(fa[x]);
13     beh[x]+=beh[fa[x]];
14     return fa[x]=dad;
15 }
16 inline void combine(int x,int y)
17 {
18     x=find(x),y=find(y);
19     if(x==y) return ;
20     beh[x]+=sum[y];
21     sum[y]+=sum[x];
22     fa[x]=y;
23 }
24
25 int main()
26 {
27     for(int i=1;i<N;i++)
28         fa[i]=i,sum[i]=1;
29     int p,u,v; scanf("%d",&p);
30     for(char ch;p--;)
31     {
32         scanf("\n%c%d",&ch,&u);
33         if(ch==‘M‘)
34         {
35             scanf("%d",&v);
36             combine(u,v);
37         }
38         else find(u),printf("%d\n",beh[u]);
39     }
40     return 0;
41 }