clang的long double问题

123456789101112131415161718192021222324252627#include <iomanip>
#include <iostream>
using namespace std;
using ld = long double;
int n, m;
ld dp[1007][1007];
ld pw[1007];
signed main() {
  cin.tie(nullptr);
  cout.tie(nullptr);
  ios::sync_with_stdio(false);
  cin >> n >> m;
  pw[0] = 1.0l;
  for (int i = 1; i <= n; i++)
    pw[i] = pw[i - 1] * 0.5l;
  dp[1][1] = 1.0l;
  for (int i = 2; i <= n; i++) {
    ld num = 1.0l / 6.0l;
    for (int j = 2; j <= i; j++)
      num = num / 2.0l + dp[i - 1][j - 1] / 3.0l;
    dp[i][i] = num / (1 - pw[i]);
    dp[i][1] = 1.0l / 6.0l + dp[i][i] / 2.0l;
    for (int j = 2; j < i; j++)
      dp[i][j] = dp[i][j - 1] / 2.0l + dp[i - 1][j - 1] / 3.0l;
  }
  cout << fixed << setprecision(9) << dp[n][m] << '\n';
}