PTA 7-2 小字辈 (25分)

Posted 2021-03-03 kreamyu

这题竟然没有卡时间，有需要可以参考一下。

#include<cstdio>
#include<cstring>
#include<string>
#include<iostream>
#include<vector>
#include<algorithm>
using namespace std;

const int N = 100001;
struct Node
{
	vector<int> hz;
	int bf;
	int fm;
}a[N];

int ans[100001]; int top = -1;
int xam = -1;
void bff(int i, int n)
{
	a[i].bf = n;
	if (n > xam)xam = n;
	for (int j = 0; j < a[i].hz.size(); j++)
	{
		bff(a[i].hz[j], n + 1);
	}
}


int main()
{
	int n, temp;
	cin >> n;
	for (int i = 1; i <= n; i++)
	{
		a[i].fm = -2;
		a[i].bf = -2;
	}
	int s;
	for (int i = 1; i <= n; i++)
	{
		scanf("%d", &temp);
		a[i].fm = temp;
		if (temp == -1) s = i;
		else
			a[temp].hz.push_back( i);
	}

	bff(s, 1);
	cout << xam << endl;
	for (int i = 1; i <= n; i++)
	{
		if (a[i].bf == xam)
		{
			ans[++top] = i;
		}
	}
	for (int i = 0; i < top; i++)
	{
		printf("%d ", ans[i]);
	}
	printf("%d", ans[top]);
	return 0;
}