func_code_string: #include <bits/stdc++.h>   using namespace std;   int main() {     ios_base::sync_with_stdio(false);     cin.tie(nullptr);     int t;     cin >> t;     while (t--) {       int n, l;       cin >> n >> l;       vector<int> a(n);       for (int i = 0; i < n; i++) {         cin >> a[i];       }       int il = 0, ir = n - 1, sl = 1, sr = 1;       double time = 0, pl = 0, pr = l;       while (il <= ir) {         double tl = (a[il] - pl) / sl, tr = (pr - a[ir]) / sr;         if (tl < tr) {           pl = a[il];           pr -= sr * tl;           il++;           sl++;           time += tl;         } else {           pr = a[ir];           pl += sl * tr;           ir--;           sr++;           time += tr;         }       }       cout << fixed << setprecision(15) << time + (pr - pl) / (sr + sl) <<   n ;     }     return 0;   }   