#include<bits/stdc++.h>
using namespace std;
int n,c,t,ans;
long long a[200005],b[200005];
long long sum[200005];
int p[200005],rp[200005];
bool cmp(int x,int y){
return b[x]<b[y];
}
int col(int x){
if(a[x]+x>c)return 0;
int l=0,r=n;
long long w;
while(l<r){
int mid=(l+r+1)/2;
w=sum[mid]+a[x]+x;
if(rp[x]<=mid){
w-=b[x];
}
if(w<=c){
l=mid;
}
else {
r=mid-1;
}
}
return l+(rp[x]>l);
}
int main(){
scanf("%d",&t);
while(t--){
scanf("%d%d",&n,&c);
for(int i=1;i<=n;++i){
scanf("%lld",&a[i]);
b[i]=a[i]+min(i,n-i+1);
p[i]=i;
}
sort(p+1,p+n+1,cmp);
for(int i=1;i<=n;++i){
sum[i]=sum[i-1]+b[p[i]];
rp[p[i]]=i;
}
for(int i=1;i<=n;++i){
ans=max(ans,col(i));
}
printf("%d\n",ans);
}
return 0;
}格式化