feat(cpp): add hhcn

cpp/hhcn.cpp

@@ -0,0 +1,14 @@
+#include <bits/stdc++.h>
+using namespace std;
+
+int main() {
+    long long A, B, C;
+    cin >> A >> B >> C;
+
+    long long a = sqrt((long double)A * C / B);
+    long long b = sqrt((long double)A * B / C);
+    long long c = sqrt((long double)B * C / A);
+
+    cout << 4 * (a + b + c);
+    return 0;
+}