试题 历届真题 【第十二届】【省赛】【A组】JAVA 蓝桥杯

package zhenti;

import java.util.ArrayList;
import java.util.HashMap;
import java.util.Scanner;

public class zuohaiziyouxiangdi{
	public static void main(String[] args) {
		Scanner scanner = new Scanner(System.in);
		int n = scanner.nextInt();
		HashMap> hashMap = new HashMap<>();
		for (int zijiedian = 2; zijiedian <= n; zijiedian++) {
			int fujiedian = scanner.nextInt();
			hashMap.putIfAbsent(fujiedian, new ArrayList<>());
			hashMap.get(fujiedian).add(zijiedian);
		}
		int ans = dfs(1, hashMap);
		System.out.println(ans);
	}
	
	public static int dfs(int fujiedian, HashMap> hashMap) {
		if (!hashMap.containsKey(fujiedian)) {
			return 0;
		}else {
			ArrayList zijiediansArrayList = hashMap.get(fujiedian);
			int zijiediangeshu = zijiediansArrayList.size();
			int zishuzuida = 0;
			for(Integer zijiedian: zijiediansArrayList) {
				zishuzuida = Math.max(dfs(zijiedian, hashMap), zishuzuida);
			}
			return zijiediangeshu + zishuzuida;
		}
	}
}