题解 | 小红的树

import java.util.*;

// 注意类名必须为 Main, 不要有任何 package xxx 信息
public class Main {
    public static void main(String[] args) {
        Scanner in = new Scanner(System.in);
        int n = in.nextInt();
        ArrayList<HashSet<Integer>> list = new ArrayList<>();
        for(int i = 0;i<=n;i++) list.add(new HashSet<>());
        for(int i = 2;i<=n;i++){
            list.get(in.nextInt()).add(i);
        }
        in.nextLine();
        char[] color = in.nextLine().toCharArray();
        int[] dp = new int[n+1]; 

        count(list,dp,color,1);
        int optNum = in.nextInt();
        for(int i = 0;i<optNum;i++){
            System.out.println(dp[in.nextInt()]);
        }
    }
    private static int count(ArrayList<HashSet<Integer>> list,int[] dp,char[] color, int curNode){
        if(color[curNode-1]=='R') dp[curNode] = 1;
        for(int child:list.get(curNode)){
            dp[curNode]+=count(list,dp,color,child);
        }
        return dp[curNode];
    }
}