#include<cstdio>#include<cstring>#include<iostream>using namespace std;const int maxn=1000005;int ll[maxn],cnt,num,ans,a,b,aa,bb;bool flag,vis[maxn];struct str{ int node,fa,ls,rs;}edge[maxn];void creat(int n){ cnt=0;num=n; edge[++cnt].fa=2,edge[cnt].ls=-1,edge[cnt].rs=-1,edge[cnt].node=1; edge[++cnt].fa=-1,edge[cnt].ls=1,edge[cnt].rs=-1,edge[cnt].node=++num; for(int i=1,now=1,tot=0;i<n;i++,tot=0) { while(tot<ll[i]) { tot++; if(edge[now].node-n<=0)now=edge[now].fa; else { if(edge[now].ls==-1) { edge[++cnt].fa=now,edge[cnt].ls=-1,edge[cnt].rs=-1; edge[now].ls=cnt; if(tot==ll[i])edge[cnt].node=i+1; else edge[cnt].node=++num; now=cnt; } else if(edge[now].rs==-1) { edge[++cnt].fa=now,edge[cnt].ls=-1,edge[cnt].rs=-1; edge[now].rs=cnt; if(tot==ll[i])edge[cnt].node=i+1; else edge[cnt].node=++num; now=cnt; } else { if(edge[now].fa==-1) { edge[++cnt].fa=-1,edge[cnt].ls=now; edge[cnt].rs=-1,edge[cnt].node=++num; edge[now].fa=cnt; now=cnt; } else now=edge[now].fa; } } } } for(int i=1;i<=cnt;i++) { if(edge[i].node==a)aa=i; else if(edge[i].node==b)bb=i; }}void out(int root){ cout<<edge[root].node<<" "<<edge[edge[root].fa].node<<" "<<edge[edge[root].ls].node<<" "<<edge[edge[root].rs].node<<endl; if(edge[root].ls!=-1)out(edge[root].ls); if(edge[root].rs!=-1)out(edge[root].rs );}void dfs(int root,int dep,int tar){ if(flag)return; if(root==tar){flag=true;ans=dep;return;} if(!vis[edge[root].fa]&&edge[root].fa!=-1) vis[edge[root].fa]=true,dfs(edge[root].fa,dep+1,tar); if(!vis[edge[root].ls]&&edge[root].ls!=-1) vis[edge[root].ls]=true,dfs(edge[root].ls,dep+1,tar); if(!vis[edge[root].rs]&&edge[root].rs!=-1) vis[edge[root].rs]=true,dfs(edge[root].rs,dep+1,tar);}int main(){ int cas,n; cin>>cas; while(cas--) { cin>>n; for(int i=1;i<n;i++)cin>>ll[i]; cin>>a>>b; creat(n); memset(vis,0,sizeof(vis)); flag=false; dfs(aa,0,bb); cout<<ans<<endl; } return 0;}
