переписали функцию input_data

main.cpp

@@ -11,28 +11,27 @@ struct Input {
 };
 
 Input
-input_data() {
+input_data(istream& in) {
     cerr << "Enter number count, numbers and bin count: ";
 
     size_t number_count;
-    cin >> number_count;
+    in >> number_count;
 
-    Input in;
-    in.numbers.resize(number_count);
+    Input input;
+    input.numbers.resize(number_count);
 
     for (size_t i = 0; i < number_count; i++) {
-        cin >> in.numbers[i];
+        in >> input.numbers[i];
     }
 
-    cin >> in.bin_count;
+    in >> input.bin_count;
 
-    return in;
+    return input;
 }
 
-
 int
 main() {
-    auto in = input_data();
+    auto in = input_data(cin);
     auto bins = make_histogram(in.numbers, in.bin_count);
     show_histogram_svg(bins);