Cube Stacking
| Time Limit: 2000MS | Memory Limit: 30000K | |
| Total Submissions: 24452 | Accepted: 8563 | |
| 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.
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.
* 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
#include<iostream>
#include<cstdio>
#include<cstring>
#define maxn 30001
using namespace std;
int father[maxn],n,m,sum[maxn],cnt[maxn];
int find(int x){
if(x==father[x]) return x;
int fa=father[x];
father[x]=find(father[x]);
cnt[x]+=cnt[fa];
return father[x];
}
void megre(int x,int y){// x,y是其本身那一坨的祖宗
father[y]=x;
cnt[y]=sum[x];
sum[x]+=sum[y];
sum[y]=0;
}
int main()
{
for(int i=1;i<=maxn;i++) father[i]=i,sum[i]=1;
char ch[8];
int x,y;
scanf("%d",&m);
while(m--){
cin>>ch+1;
if(ch[1]=='M'){
scanf("%d%d",&x,&y);
int rx=find(x),ry=find(y);
megre(rx,ry);
}
else{
scanf("%d",&x);
int rx=find(x);
printf("%d
",sum[rx]-cnt[x]-1);
}
}
return 0;
}
思路：加权并查集例题