zjy代码（scy微改）：

#include<bits/stdc++.h>
using namespace std;
const int N=1e6+10;
int dep[N],fa[N],sonsiz[N];
 
int main()
{
    int n;scanf("%d",&n);
    memset(dep,0,sizeof(dep));
    memset(sonsiz,0,sizeof(sonsiz));
    for(int i=1,x;i<=n;i++)
    {
        scanf("%d",&fa[i]); 
        dep[i]=dep[fa[i]]+1;
        sonsiz[fa[i]]++;
    }
    int m=0;for(int i=1;i<=n;i++){if(sonsiz[i]==0)m++;}
 
    for(int i=1,x;i<=m;i++)
    {
        scanf("%d",&x);
        if(i==m){puts("0");continue;}
 
        x=fa[x];//目标是让x指向最后一个无法确认的点
        while(sonsiz[x]==1&&x!=0)x=fa[x];
        sonsiz[x]--;
        
        printf("%d\n",dep[x]+1);
    }
    return 0;
}

zjy代码（scy微改）：

#include<bits/stdc++.h>
using namespace std;
const int N=1e6+10;
int dep[N],fa[N],sonsiz[N];
 
int main()
{
    int n;scanf("%d",&n);
    memset(dep,0,sizeof(dep));
    memset(sonsiz,0,sizeof(sonsiz));
    for(int i=1,x;i<=n;i++)
    {
        scanf("%d",&fa[i]); 
        dep[i]=dep[fa[i]]+1;
        sonsiz[fa[i]]++;
    }
    int m=0;for(int i=1;i<=n;i++){if(sonsiz[i]==0)m++;}
 
    for(int i=1,x;i<=m;i++)
    {
        scanf("%d",&x);
        if(i==m){puts("0");continue;}
 
        x=fa[x];//目标是让x指向最后一个无法确认的点
        while(sonsiz[x]==1&&x!=0)x=fa[x];
        sonsiz[x]--;
        
        printf("%d\n",dep[x]+1);
    }
    return 0;
}