题解——CF Manthan, Codefest 18 (rated, Div. 1 + Div. 2) T4（模拟）

随便模拟下就过了qwq

然后忘了特判WA了QwQ

#include <cstdio>
#include <algorithm>
#include <cstring>
#include <set>
#include <queue>
using namespace std;
int n,u[400010],v[400010],fir[200010],nxt[400010],cnt=0,dep[200010],squ[200010];
set<int> sons[200010];
void addedge(int ui,int vi){
  cnt++;
  u[cnt]=ui;
  v[cnt]=vi;
  nxt[cnt]=fir[ui];
  fir[ui]=cnt;
}
void dfs(int u,int f){
  for(int i=fir[u];i;i=nxt[i]){
    if(v[i]==f)
      continue;
    dep[v[i]]=dep[u]+1;
    sons[u].insert(v[i]);
    dfs(v[i],u);
  }
}
int main(){
  scanf("%d",&n);
  for(int i=1;i<=n-1;i++){
    int a,b;
    scanf("%d %d",&a,&b);
    addedge(a,b);
    addedge(b,a);
  }
  queue<int> q;
  for(int i=1;i<=n;i++)
    scanf("%d",&squ[i]);
  dep[1]=1;
  dfs(1,0);
  q.push(squ[1]);
  for(int i=1;i<=n;){
    if (q.empty()&&i==n) {
      break;
    }
    else if(q.empty()&&i!=n){
      printf("No
");
      return 0;
    }
      int x=q.front();
      q.pop();
      for(int j=1;j<=sons[x].size();j++){
        if(sons[x].count(squ[i+j])){
          q.push(squ[i+j]);
          continue;
        }
        else{
          printf("No
");
          return 0;
        }
      }
      i+=sons[x].size();
    }
  printf("Yes
");
  return 0;
}