Рефакторинг: разделение кода на функции

histogram.cpp

@@ -3,8 +3,13 @@
 #include <vector>
 using namespace std;
 
-void find_minmax(const vector<double>& numbers, double& minN, double& maxN)
+//std::vector<size_t>
+bool find_minmax(const vector<double>& numbers, double& minN, double& maxN)
 {
+    if (numbers.empty()) {
+        minN = maxN = 0;
+        return false;
+    }
     minN = numbers[0];
     maxN = numbers[0];
 
@@ -19,6 +24,7 @@ void find_minmax(const vector<double>& numbers, double& minN, double& maxN)
             maxN = x;
         }
     }
+    return true;
 }
 
 vector<size_t> make_histogram(const vector<double>& numbers, size_t bin_count)

histogram_internal.h

@@ -3,7 +3,7 @@
 
 #include <vector>
 
-std::vector<size_t>
-find_minmax( const std::vector<double>& numbers, double& minN, double& maxN);
+//std::vector<size_t>
+bool find_minmax(const std::vector<double>& numbers, double& minN, double& maxN);
 
 #endif // HISTOGRAM_INTERNAL_H_INCLUDED