func_code_string: #include <bits/stdc++.h>   using namespace std;   const int N = 2e5 + 10;   const int inf = 0x3f3f3f3f;   const int mod = 998244353;   int a[N], n, L;   bool check(double x, int id) {     double s1 = 0, s2 = 0;     double t = x;     int s = 1;     for (int i = 1; i <= n + 1; i++) {       double cur = 1.0 * (a[i] - a[i - 1]) / s;       if (cur <= t) {         s1 = a[i];         t -= cur;       } else {         s1 += t * s;         break;       }       s++;     }     s = 1;     t = x;     for (int i = n; i >= 0; i--) {       double cur = 1.0 * (a[i + 1] - a[i]) / s;       if (cur <= t) {         s2 = L - a[i];         t -= cur;       } else {         s2 += t * s;         break;       }       s++;     }     return s1 + s2 >= 1.0 * L;   }   void solve() {     scanf( %d%d , &n, &L);     for (int i = 1; i <= n; i++) {       scanf( %d , &a[i]);     }     a[n + 1] = L;     double l = 0, r = L;     double res = 1e9;     for (int i = 1; i <= 100; i++) {       double mid = 1.0 * (l + r) / 2;       if (check(mid, i)) {         res = mid;         r = mid;       } else         l = mid;     }     printf( %.6f n , res);   }   int main() {     int t;     cin >> t;     while (t--) solve();     return 0;   }   