support bazel complie this project and format code.

learn_class/modern_cpp_30/compilercompute/factorial.cpp

@@ -0,0 +1,20 @@
+//
+// Created by light on 19-12-28.
+//
+
+#include <iostream>
+
+using namespace std;
+
+template <int n> struct factorial {
+  static_assert(n >= 0, "Arg must be non-negative");
+  static const int value = n * factorial<n - 1>::value;
+};
+
+template <> struct factorial<0> { static const int value = 1; };
+
+int main() {
+
+  printf("%d\n", factorial<10>::value);
+  return 0;
+}