protect

histogram.cpp

@@ -2,21 +2,29 @@
 
 using namespace std;
 
-void find_minmax(const vector<double>& numbers, double& min, double& max) {
-    min = numbers[0];
-    max = numbers[0];
 
-    for (double x : numbers)
-    {
-        if (x < min)
+
+bool find_minmax(const vector<double>& numbers, double& min, double& max) {
+    if (!(numbers.empty())) {
+        min = numbers[0];
+        max = numbers[0];
+        for (double x : numbers)
         {
-            min = x;
-        }
-        else if (x > max)
-        {
-            max = x;
+            if (x < min)
+            {
+                min = x;
+            }
+            else if (x > max)
+            {
+                max = x;
+            }
         }
+        return true;
     }
+    else {
+        return false;
+    }
+
 }
 
 vector<size_t> make_histogram(const vector<double>& numbers, size_t bin_count)

histogram_internal.h

@@ -4,6 +4,6 @@
 #include <vector>
 #include <iostream>
 
-void find_minmax(const std::vector<double>& numbers, double& min, double& max);
+bool find_minmax(const std::vector<double>& numbers, double& min, double& max);
 
 #endif // HISTOGRAM_INTERNAL_H_INCLUDED

svg.cpp

@@ -37,8 +37,8 @@ void show_histogram_svg(const vector<size_t>& bins)
     const double IMAGE_HEIGHT = 300;
     const double TEXT_LEFT = 20;
     const double TEXT_BASELINE = 20;
-    const double TEXT_WIDTH = 50;
-    const double BIN_HEIGHT = 30;
+    const double TEXT_HEIGHT = 20;
+    const double BIN_WIDTH = 30;
     const double BLOCK_WIDTH = 10;
 
     svg_begin(IMAGE_WIDTH, IMAGE_HEIGHT);
@@ -52,23 +52,25 @@ void show_histogram_svg(const vector<size_t>& bins)
         }
     }
 
-    double max_width = IMAGE_WIDTH - TEXT_WIDTH;
-    double top = 0;
+    double max_height = IMAGE_HEIGHT - TEXT_HEIGHT - BLOCK_WIDTH;
+
+    double left = TEXT_LEFT;
+
     for (size_t count : bins)
     {
         double bin_width;
         if (max_count > 0)
         {
-            bin_width = static_cast<double>(count) / max_count * max_width;
+            bin_height = static_cast<double>(count) / max_count * max_height;
         }
         else
         {
-            bin_width = 0.0;
+            bin_height = 0.0;
         }
 
-        svg_text(TEXT_LEFT, top + TEXT_BASELINE, to_string(count));
-        svg_rect(TEXT_WIDTH, top, bin_width, BIN_HEIGHT, "blue", "#aaffaa");
-        top += BIN_HEIGHT;
+        svg_text(left + BIN_WIDTH/2.0, IMAGE_HEIGHT - 5 ,to_string(count));
+        svg_rect(left, IMAGE_HEIGHT - bin_height, BIN_WIDTH, bin_height, "blue", "#aaffaa");
+        left += BIN_WIDTH + BLOCK_WIDTH ;
     }
     svg_end();
 }

unittest.cpp

@@ -42,3 +42,10 @@ TEST_CASE("positive and negative numbers")
     CHECK(min == -3);
     CHECK(max == 5);
 }
+TEST_CASE("none elements")
+{
+    double min = 0;
+    double max = 0;
+    CHECK(!(find_minmax({}, min, max)));
+}
+