Published at Feb 26 2019
·
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Instructions

Test suite

Solution

A Pythagorean triplet is a set of three natural numbers, {a, b, c}, for which,

```
a**2 + b**2 = c**2
```

For example,

```
3**2 + 4**2 = 9 + 16 = 25 = 5**2.
```

There exists exactly one Pythagorean triplet for which a + b + c = 1000.

Find the product a * b * c.

To run the tests run the command `go test`

from within the exercise directory.

If the test suite contains benchmarks, you can run these with the `--bench`

and `--benchmem`

flags:

```
go test -v --bench . --benchmem
```

Keep in mind that each reviewer will run benchmarks on a different machine, with different specs, so the results from these benchmark tests may vary.

For more detailed information about the Go track, including how to get help if you're having trouble, please visit the exercism.io Go language page.

Problem 9 at Project Euler http://projecteuler.net/problem=9

It's possible to submit an incomplete solution so you can see how others have completed the exercise.

```
package pythagorean
// Use this type definition,
//
// type Triplet [3]int
//
// and implement two functions,
//
// Range(min, max int) []Triplet
// Sum(p int) []Triplet
//
// Range returns a list of all Pythagorean triplets with sides in the
// range min to max inclusive.
//
// Sum returns a list of all Pythagorean triplets where the sum a+b+c
// (the perimeter) is equal to p.
//
// The three elements of each returned triplet must be in order,
// t[0] <= t[1] <= t[2], and the list of triplets must be in lexicographic
// order.
import (
"reflect"
"testing"
)
var rangeTests = []struct {
min, max int
ts []Triplet
}{
{1, 10, []Triplet{{3, 4, 5}, {6, 8, 10}}},
{11, 20, []Triplet{{12, 16, 20}}},
}
func TestRange(t *testing.T) {
for _, test := range rangeTests {
ts := Range(test.min, test.max)
if !reflect.DeepEqual(ts, test.ts) {
t.Fatalf("Range(%d, %d) = %v, want %v",
test.min, test.max, ts, test.ts)
}
}
}
var sumTests = []struct {
sum int
ts []Triplet
}{
{180, []Triplet{{18, 80, 82}, {30, 72, 78}, {45, 60, 75}}},
{1000, []Triplet{{200, 375, 425}}},
}
func TestSum(t *testing.T) {
for _, test := range sumTests {
ts := Sum(test.sum)
if !reflect.DeepEqual(ts, test.ts) {
t.Fatalf("Sum(%d) = %v, want %v",
test.sum, ts, test.ts)
}
}
}
func BenchmarkRange(b *testing.B) {
for i := 0; i < b.N; i++ {
Range(1, 100)
}
}
func BenchmarkSum(b *testing.B) {
for i := 0; i < b.N; i++ {
Sum(1000)
}
}
```

```
package pythagorean
// Triplet is a Pythagorean triplet.
// A Pythagorean triplet is a set of three natural numbers, {a, b, c}, for which, a**2 + b**2 = c**2.
type Triplet [3]int
// Range returns a list of all Pythagorean triplets with sides in the
// range min to max inclusive.
func Range(min int, max int) []Triplet {
result := make([]Triplet, 0)
for a := min; a < max-1; a++ {
for b := a + 1; b < max; b++ {
for c := b + 1; c < max+1; c++ {
if a*a+b*b == c*c {
result = append(result, [3]int{a, b, c})
}
}
}
}
return result
}
// Sum returns a list of all Pythagorean triplets where the sum a+b+c
// (the perimeter) is equal to p.
// a less b less c therefore a less sum / 3; b less (sum - 1) / 2
func Sum(sum int) []Triplet {
result := make([]Triplet, 0)
for a := 1; a < sum/3; a++ {
for b := a + 1; b < (sum-1)/2; b++ {
c := sum - a - b
if a*a+b*b == c*c {
result = append(result, [3]int{a, b, c})
}
}
}
return result
}
```

A huge amount can be learned from reading other people’s code. This is why we wanted to give exercism users the option of making their solutions public.

Here are some questions to help you reflect on this solution and learn the most from it.

- What compromises have been made?
- Are there new concepts here that you could read more about to improve your understanding?

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