COGS——C2274. [HEOI 2016] tree

 1 #include <algorithm>
 2 #include <iostream>
 3 #include <cstdio>
 4 
 5 using namespace std;
 6 
 7 const int N(1e6+15);
 8 int n,q,u,v;
 9 
10 int mark[N],dad[N];
11 int Get_grandfa(int x,int y)
12 {
13     for(;!mark[x];)
14         x=dad[x];
15     return x;
16 }
17 
18 int main()
19 {
20     freopen("heoi2016_tree.in","r",stdin);
21     freopen("heoi2016_tree.out","w",stdout);
22     scanf("%d%d",&n,&q);
23     for(int i=1;i<n;i++)
24         scanf("%d%d",&u,&v),dad[v]=u;
25     mark[1]=1;
26     for(char op;q--;)
27     {
28         cin>>op>>v;
29         if(op==‘C‘) mark[v]=1;
30         else printf("%d\n",Get_grandfa(v,1));
31     }
32     return 0;
33 }