D - Poisoned Dagger

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

const int N=110;
ll n,m;
ll a[N];

bool check(ll x){
    ll sum=0;
    for(ll i=1;i<n;i++){
        sum+=min(x,a[i+1]-a[i]);
    }
    sum+=x;
    return sum>=m;
}

int main()
{
    int t;
    cin>>t;
    while(t--){
        cin>>n>>m;
        for(ll i=1;i<=n;i++){
            cin>>a[i];
        }
        ll l=0,r=m;
        while(l<r){
            ll mid=l+r>>1;
            if(check(mid)){
                r=mid;
            }
            else l=mid+1;
        }
        cout<<l<<endl;
    }
    return 0;
}