POJ1988 Cube Stacking (！hard）

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.  题目大意：（同银河舰队传说） 对于n块积木，进行两种操作：M a b 把a移到b上，C a 询问a下面有几块积木。 思路：用并查集和tot，sum数组维护，像银河一样简单AC。。。 code： #include<iostream> #include<cstdio> using namespace std; int fa[30001]={0},sum[30001]={0},len[30001]={0}; int rool(int x) { int j; if (fa[x]!=x) { j=rool(fa[x]); len[x]=len[x]+len[fa[x]]; fa[x]=j; } return fa[x]; } int main() { int p,n,i,j,r1,r2,x,y; char ch; scanf("%d",&p); n=30000; for (i=1;i<=n;++i) {   fa[i]=i;   sum[i]=1;     }     for (i=1;i<=p;++i)     {      scanf("%*c%c",&ch);      if (ch=='M')      {      scanf("%d%d",&x,&y);      r1=rool(x);      r2=rool(y);      if (r1!=r2)      {      len[r1]=len[r1]+sum[r2]; sum[r2]=sum[r2]+sum[r1]; fa[r1]=r2;      }      }      else      {      scanf("%d",&x);      r1=rool(x);      printf("%d\n",len[x]);      }     } }