POJ1988：Cube Stacking（并查集）

Cube Stacking

Time Limit: 2000MS Memory Limit: 30000KTotal Submissions: 24664 Accepted: 8652Case 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

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

Sample Output

102

Source

USACO 2004 U S Open

思路：简单并查集，num[i]记录i点距离根节点多远，sum[i]记录i的儿子+自己数量。

# include <iostream># include <cstring># include <cstdio># include <algorithm># define MAXN 30000using namespace std;int pre[MAXN+1], sum[MAXN+1], num[MAXN+1];int find(int x){    if(x == pre[x])        return pre[x];    else    {        int t = pre[x];        pre[x] = find(pre[x]);        num[x] = num[t] + num[x];        return pre[x];    }}int main(){    int p, a, b;    char c;    while(~scanf("%d",&p))    {        for(int i=1; i<=MAXN; ++i)        {            pre[i] = i;            sum[i] = 1;            num[i] = 0;        }        while(p--)        {            getchar();            c = getchar();            if(c == 'M')            {                scanf("%d%d",&a,&b);                int px = find(a);                int py = find(b);                if(px != py)                {                    pre[px] = py;                    num[px] = sum[py];                    sum[py] += sum[px];                }            }            else            {                scanf("%d",&a);                find(a);                printf("%d\n",num[a]);            }        }    }    return 0;}