求助（关于神秘问题）

#include <bits/stdc++.h>
using namespace std;

#define maxN 2000005
#define mod 998244353

int n;

int fa[maxN],dep[maxN],r[maxN];//r[x]=0->the same
void init()
{
	for(int i = 1; i <= n; i++)
		fa[i] = i;
	return;
}
int find(int x)
{
	if(fa[x] == x)
		return x;
	int anc = find(fa[x]);
	r[x] = (r[fa[x]]+r[x])%2;
	fa[x] = anc;
	return anc;
}
void merge(int x,int y,int w)
{
	int a = find(x),b = find(y);
    fa[a] = b;
	r[a] = (r[x] + r[y] + w + 1) % 2;
	return;
}
int main()
{
	ios::sync_with_stdio(0);
	cin.tie(0);
	cout.tie(0);
	cin >> n;
	init();
	int v,opt;
	for(int i = 1; i <= n; i++)
	{
		cin >> v >> opt;
		if(find(v) != find(i))
		{
			merge(i,v,opt);
		}
		else
		{
			if((r[v] + r[i] + 1) % 2 != opt)
			{
				cout << "No answer\n";
				return 0;
			}
		}
	}
	long long ans = 1,res1 = 0,res2 = 0;
	int cnt[maxN][2];
	for(int i = 1; i <= n; i++)
		cnt[find(i)][r[i]]++;
	for(int i = 1; i <= n; i++)
	{
		if(find(i) == i)
        {
            ans = (ans * 2) % mod;
			res1 += max(cnt[i][0],cnt[i][1]);
			res2 += min(cnt[i][0],cnt[i][1]);
		}
	}
	cout << ans << '\n';
	cout << res1 << '\n';
	cout << res2 << '\n';
	return 0;
}