能随机,但不多

#include<bits/stdc++.h>
#define ll long long
#define ull unsigned long long
template<class T>inline void read(T &x){
	x=0;bool f=0;char c=getchar();
	for(;!isdigit(c);c=getchar())if(c=='-')f=1;
	for(;isdigit(c);c=getchar())x=(x<<3)+(x<<1)+c-'0';
	if(f)x=-x;return;
}
template<class T>inline void write(T x){
	if(x<0){putchar('-');x=-x;}
	if(x>9)write(x/10);
	putchar(x%10+'0');
	return;
}
using namespace std;
const int RANDTIME=4500;
int n,t,a[500010];
bool vis[500010];
inline void solve(){
	for(int i=1;i<n;++i){
		vis[a[i]]=1;
		if(!(i^1)||!(a[i]^1))continue;
		if(a[i]<=RANDTIME){
			for(int b=1;b<a[i];++b){
				if((2*a[i]-b<=n)&&((vis[b]&&!vis[2*a[i]-b])||(vis[2*a[i]-b]&&!vis[b]))){
					puts("Y");return;
				}
			}
		}else{
			for(int j=1;j<=RANDTIME;++j){
				int b=rand()%(a[i]-1)+1;
				if((2*a[i]-b<=n)&&((vis[b]&&!vis[2*a[i]-b])||(vis[2*a[i]-b]&&!vis[b]))){
					puts("Y");return;
				}
			}
		}
	}
	puts("N");return;
}
signed main(){
	srand(time(NULL));
	read(t);
	while(t--){
		read(n);memset(vis,0,sizeof vis);
		for(int i=1;i<=n;++i)read(a[i]);
		solve();
	}
}