D

TaskD.java

package com.mehdi.main.codeforces.codefest18;

import com.mehdi.lib.GraphUtils;
import com.mehdi.lib.io.InputReader;
import java.io.PrintWriter;
import java.util.ArrayDeque;
import java.util.Arrays;
import java.util.HashSet;
import java.util.List;

import static com.mehdi.lib.Factories.*;

public class TaskD {

  List<Integer>[] g;
  int n;
  int[] lev, seq;

  void bfs(int cur) {
    lev[cur] = 1;
    ArrayDeque<Integer> q = new ArrayDeque<>();
    q.add(cur);
    while (!q.isEmpty()) {
      int u = q.poll();
      for (int v : g[u]) {
        if (lev[v] == 0) {
          lev[v] = lev[u] + 1;
          q.add(v);
        }
      }
    }
  }

  public void solve(int testNumber, InputReader in, PrintWriter out) {
    n = in.nextInt();
    g = GraphUtils.generateGraph(n + 1);
    lev = new int[n + 1];
    seq = new int[n + 1];
    for (int i = 0; i < n - 1; i++) {
      int u = in.nextInt();
      int v = in.nextInt();
      g[u].add(v);
      g[v].add(u);
    }
    for (int i = 1; i <= n; i++) {
      seq[i] = in.nextInt();
    }
    bfs(1);
    if (seq[1] != 1) {
      out.println("No");
      return;
    }
    int level = 1;
    int[] arr = new int[n + 1];
    int pt = 0;
    for (int i = 1; i <= n; i++) {
      int u = seq[i];
      if (lev[u] < level) {
        out.println("No");
        return;
      }
      arr[pt++] = lev[u];
      level = lev[u];
    }
    for (int i = 1; i < pt; i++) {
      if (arr[i] < arr[i - 1]) {
        out.println("No");
        return;
      }
    }
    out.println("Yes");
  }
}