Darts - is there an inconsistency between the tests and the overview page description?

[armhzjz]

According to the overview page of the Darts problem, the radius of the concentric circles are defined as:

The outer circle has a radius of 10 units (this is equivalent to the total radius for the entire target), the middle circle a radius of 5 units, and the inner circle a radius of 1. Of course, they are all centered at the same point (that is, the circles are concentric defined by the coordinates (0, 0).

However, the test "test_just_outside_the_middle_circle" is defined as:

{
   coordinate_t landing_position = { -3.6F, -3.6F };
   uint8_t expected = 1;
   uint8_t actual = score(landing_position);
   TEST_ASSERT_EQUAL_UINT8(expected, actual);
}

This is confusing because, (also according to the overview page of the Darts problem) the expected number of points for positions under the radius of 5.0 (i.e. middle circle) should be 5 (not 1). This causes the tests to failed (or pushes the user to implement something that passes the test - ignoring the specification of the problem).

I see more discrepancies between some other tests and the specification of the problem. Am I missing something? I see the overview page was recently updated (Dec. 2022). Were the tests not updated as well?

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[armhzjz]

The very first test is inconsistent with the second test. The first test is defined as:

static void test_missed_target(void)
{
   coordinate_t landing_position = { -9.0F, 9.0F };
   uint8_t expected = 0;
   uint8_t actual = score(landing_position);
   TEST_ASSERT_EQUAL_UINT8(expected, actual);
}

while the second test is defined as:

Some basic Git commands are:

static void test_on_the_outer_circle(void)
{
      // delete this line to run test
   coordinate_t landing_position = { 0.0F, 10.0F };
   uint8_t expected = 1;
   uint8_t actual = score(landing_position);
   TEST_ASSERT_EQUAL_UINT8(expected, actual);
}

Shouldn't the expected values be 1 and 1 respectively?

[ryanplusplus]

According to the overview page of the Darts problem, the radius of the concentric circles are defined as:

The outer circle has a radius of 10 units (this is equivalent to the total radius for the entire target), the middle circle a radius of 5 units, and the inner circle a radius of 1. Of course, they are all centered at the same point (that is, the circles are concentric defined by the coordinates (0, 0).

However, the test "test_just_outside_the_middle_circle" is defined as:

{
   coordinate_t landing_position = { -3.6F, -3.6F };
   uint8_t expected = 1;
   uint8_t actual = score(landing_position);
   TEST_ASSERT_EQUAL_UINT8(expected, actual);
}

This is confusing because, (also according to the overview page of the Darts problem) the expected number of points for positions under the radius of 5.0 (i.e. middle circle) should be 5 (not 1). This causes the tests to failed (or pushes the user to implement something that passes the test - ignoring the specification of the problem).

The distance from origin to { -3.6F, -3.6F } is ~5.09 so this is outside of the middle circle and inside of the outer circle. This is consistent with the description in the overview:

If the dart lands in the outer circle of the target, player earns 1 point. If the dart lands in the middle circle of the target, player earns 5 points.

Since the distance from origin is greater than 5, it earns only 1 point.

I see more discrepancies between some other tests and the specification of the problem. Am I missing something? I see the overview page was recently updated (Dec. 2022). Were the tests not updated as well?

The problem specifications and implementations are machine-generated and not always updated in lockstep, but the changes are usually just additions, removals, or tweaks of tests, not wholesale re-definitions of the problem.

[ryanplusplus]

The very first test is inconsistent with the second test. The first test is defined as:

static void test_missed_target(void)
{
   coordinate_t landing_position = { -9.0F, 9.0F };
   uint8_t expected = 0;
   uint8_t actual = score(landing_position);
   TEST_ASSERT_EQUAL_UINT8(expected, actual);
}

while the second test is defined as:

Some basic Git commands are:

static void test_on_the_outer_circle(void)
{
      // delete this line to run test
   coordinate_t landing_position = { 0.0F, 10.0F };
   uint8_t expected = 1;
   uint8_t actual = score(landing_position);
   TEST_ASSERT_EQUAL_UINT8(expected, actual);
}

Shouldn't the expected values be 1 and 1 respectively?

For the first test, the distance from origin is ~12.73 and this is greater than 10 so 0 points are earned. I suspect that you are not correctly calculating the distance from origin. Check out the Wikipedia article on Euclidean distance.

[armhzjz]

So, what I missed, is that the function should then calculate the hypotenuse based on the Cartesian coordinates?

[armhzjz]

For the first test, the distance from origin is ~12.73 and this is greater than 10 so 0 points are earned. I suspect that you are not correctly calculating the distance from origin. Check out the Wikipedia article on Euclidean distance.

Right. Thank you very much again.