poj1988Cube Stacking 并查集

Cube Stacking

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

代码：

#include<cstdio>
using namespace std;
const int maxn = (int)3e4 + 10;
int f[maxn],root[maxn],sub[maxn];
int find(int x)
{
	if (x != f[x])
	{
		int t = f[x];
		f[x] = find(f[x]);
		sub[x] += sub[t];
	}
	return f[x];
}
void join(int x,int y)
{
	int fx = find(x),fy = find(y);
	if (fx != fy)
	{
		f[fy] = fx;
		sub[fy] = root[fx];
		root[fx] += root[fy];
	}
}
int main()
{
	int n,x,y;
	char q[3];
	scanf("%d",&n);
	for (int i = 1;i <= 30000;i ++)
		f[i] = i,root[i] = 1;
	while (n --)
	{
		scanf("%s",q);
		if (q[0] == 'M')
		{
			scanf("%d %d",&x,&y);
			join(x,y);
		}
		else
		{
			scanf("%d",&x);
			printf("%d\n",root[find(x)] - sub[x] - 1);
		}
	}
	return 0;
}