POJ1988 并查集的使用

Cube Stacking

Time Limit: 2000MS		Memory Limit: 30000K
Total Submissions: 21157		Accepted: 7395
Case Time Limit: 1000MS

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

 #include<stdio.h>
 #define N 30001

 int count[N], num[N], pre[N];

 void inite()
 {
     for(int i = ; i < N; i++)
     {
         count[i] = ;
         num[i] = ;
         pre[i] = i;
     }
 }

 int find(int x)
 {
     if(pre[x] == x)
         return x;

     int t = find(pre[x]);
     count[x] += count[pre[x]];
     pre[x] = t;
     return t;

 }
 void Union(int x, int y)
 {
     int i = find(x);
     int j = find(y);
     if(i == j)
     {
         return;
     }
     count[i] = num[j];
     num[j] += num[i];
     pre[i] = j;
 }

 int main()
 {
     int i, x, y, n;
     char s[];
     scanf("%d",&n);
     inite();
     for(i = ; i < n; i++)
     {
         scanf("%s",s);
         if(s[] == 'M')
         {
             scanf("%d%d",&x,&y);
             Union(x,y);
         }
         else if(s[] == 'C')
         {
             scanf("%d",&x);
             int c = find(x);
             printf("%d\n",count[x]);
         }
     }
     return ;
 }