func_code_string: #include <bits/stdc++.h>   using namespace std;   struct keycompare {     bool operator()(const pair<long long, long long>& v, const long long& k) {       return (v.first < k);     }     bool operator()(const long long& k, const pair<long long, long long>& v) {       return (k < v.first);     }   };   long long mod1 = 998244353, mod2 = 1000000007, limit = 9223372036854775807;   long double pi = 3.1415926535897932;   long long modpow(long long x, long long n, long long m) {     if (x > m) {       x %= m;     }     if (n == 0) return 1 % m;     long long u = modpow(x, n / 2, m);     u = (u * u) % m;     if (n % 2 == 1) u = (u * x) % m;     return u;   }   long long gcd(long long a, long long b) {     if (b == 0) return a;     return gcd(b, a % b);   }   bool isprime(long long n) {     if (n == 2) return true;     for (long long i = 2; i * i <= n; i++) {       if (n % i == 0) return false;     }     return true;   }   long long power(long long x, long long n) {     long long x_n = 1;     for (long long i = 0; i < n; i++) {       x_n *= x;     }     return x_n;   }   long double arr[100005];   int n;   long double l;   long double time1(long double mid) {     long double last = 1;     long double timer = 0;     for (int i = 1; i <= n + 1; i++) {       if (arr[i] < mid) {         timer += (arr[i] - arr[i - 1]) / last;       } else {         timer += (mid - arr[i - 1]) / last;         break;       }       last++;     }     return timer;   }   long double time2(long double mid) {     long double last = 1;     long double timer = 0;     for (int i = n; i >= 0; i--) {       if (arr[i] > mid) {         timer += (arr[i + 1] - arr[i]) / last;       } else {         timer += (arr[i + 1] - mid) / last;         break;       }       last++;     }     return timer;   }   int main() {     ios_base::sync_with_stdio(false);     cin.tie(NULL);     int t;     cin >> t;     while (t--) {       cin >> n >> l;       arr[0] = 0;       arr[n + 1] = l;       for (int i = 1; i <= n; i++) {         cin >> arr[i];       }       long double left = 0, right = l;       while (abs(left - right) > 1e-9) {         long double mid = (left + right) / 2;         if (time1(mid) < time2(mid)) {           left = mid;         } else {           right = mid;         }       }       cout << setprecision(15) << time1(left) << endl;     }   }   