[Init] Solved solutions

cpp/200B.cpp

@@ -0,0 +1,27 @@
+#include <iostream>
+#include <iomanip>
+
+using namespace std;
+
+int main() {
+    int n;
+    int *a;
+    double *arr;
+    cin >> n;
+    a = new int[n];
+    for (int i = 0; i < n; ++i)
+        a[i] = 1;
+    arr = new double[n];
+    for (int i = 0; i < n; ++i)
+        cin >> arr[i];
+    while (n > 1) {
+        for (int i = 0; i < n / 2; ++i) {
+            int sum = a[i] + a[n - i - 1];
+            arr[i] = (double) a[i] / sum * arr[i] + (double) a[n - i - 1] / sum * arr[n - i - 1];
+            a[i] = sum;
+        }
+        n = (n + 1) / 2;
+    }
+    cout << setprecision(6) << arr[0] << endl;
+    return 0;
+}