code: сделал вариант 5 через функцию

project/pr3.cbp

@@ -37,6 +37,8 @@
 		<Unit filename="histogram.h" />
 		<Unit filename="histogram_internal.h" />
 		<Unit filename="main.cpp" />
+		<Unit filename="svg.cpp" />
+		<Unit filename="svg.h" />
 		<Unit filename="text.cpp" />
 		<Unit filename="text.h" />
 		<Extensions>

project/svg.cpp

@@ -6,6 +6,12 @@
 #include "svg.h"
 using namespace std;
 
+size_t emptiness_width (size_t a, size_t b)
+{
+    size_t c = a - b;
+    return c;
+}
+
 void
 svg_begin(double width, double height)
 {
@@ -36,7 +42,6 @@ svg_rect(double x, double y, double width, double height, string stroke = "black
 
 }
 
-
 void
 show_histogram_svg(const vector<size_t>& bins)
 {
@@ -67,11 +72,10 @@ show_histogram_svg(const vector<size_t>& bins)
     for (size_t bin : bins)
     {
         double bin_width = (MAX_WIDTH)*(bin/max_count);
-        svg_rect(MAX_WIDTH-bin_width, top, bin_width, BIN_HEIGHT, BLACK, RED);
+        svg_rect(emptiness_width(MAX_WIDTH, bin_width), top, bin_width, BIN_HEIGHT, BLACK, RED);
         svg_text(TEXT_LEFT+MAX_WIDTH, top + TEXT_BASELINE, to_string(bin));
         top += BIN_HEIGHT;
     }
 
     svg_end();
 }
-

unittest.cpp

@@ -1,9 +1,11 @@
 #define DOCTEST_CONFIG_NO_MULTITHREADING
 #define DOCTEST_CONFIG_IMPLEMENT_WITH_MAIN
+#include <vector>
 #include "doctest.h"
 #include "project/histogram_internal.h"
+#include "project/svg.h"
 
-TEST_CASE("distinct positive numbers 1")
+/* TEST_CASE("distinct positive numbers 1")
 {
     double min = 0;
     double max = 0;
@@ -39,3 +41,16 @@ TEST_CASE("vector with same elements") {
     CHECK(min == 2);
     CHECK(max == 2);
 }
+
+*/
+
+TEST_CASE("distinct positive numbers 1")
+{
+    double min = 0;
+    double max = 0;
+    find_minmax({1, 2}, min, max);
+    CHECK(min == 1);
+    CHECK(max == 2);
+}
+
+