diff --git a/Luogu/problem/P4550/P4550.cpp b/Luogu/problem/P4550/P4550.cpp
new file mode 100644
index 00000000..524116d1
--- /dev/null
+++ b/Luogu/problem/P4550/P4550.cpp
@@ -0,0 +1,17 @@
+#include <bits/stdc++.h>
+
+using namespace std;
+
+int n;
+double f[10005], g[10005];
+
+int main() {
+    cin >> n;
+    f[n] = g[n] = 0;
+    for (int i = n - 1; i >= 0; i--) {
+        f[i] = f[i + 1] + 1.00 * n / (n - i);
+        g[i] = 1.00 * i / (n - i) * (2 * f[i] + 1) + g[i + 1] + 2 * f[i + 1] + 1;
+    }
+    cout << fixed << setprecision(2) << 1.00 * (g[0] + f[0]) / 2 << endl;
+    return 0;
+}