package main
import (
	"testing"
	"github.com/stretchr/testify/assert"
)
func TestHorseDual(t *testing.T) {
	cases := []struct {
		horses   int
		power    []int
		expected int
	}{
		{3, []int{5, 8, 9}, 1},
		{10, []int{5, 15, 17, 3, 8, 11, 28, 6, 55, 7}, 1},
	}
	for _, tc := range cases {
		t.Run("", func(t *testing.T) {
			assert.Equal(t, tc.expected, HorseDuals(tc.horses, tc.power))
		})
	}
}

package main
import (
	"fmt"
)
func main() {
	var horses int
	fmt.Println("How many horse are in the race?")
	fmt.Scan(&horses)
	power := make([]int, horses)
	for i := 0; i < horses; i++ {
		fmt.Printf("Horse[%d] power: ", i)
		fmt.Scan(&power[i])
	}
	fmt.Println(HorseDuals(horses, power))
}
func HorseDuals(lovak int, loero []int) (szoros int) {
	szoros = Abs(loero[0] - loero[1])
	for key, value := range loero {
		for i := key + 1; i < lovak; i++ {
			if Abs(value-loero[i]) < szoros {
				szoros = Abs(value - loero[i])
			}
		}
	}
	return
}
func Abs(x int) int {
	if x < 0 {
		return -x
	}
	return x
}

# Horse-racing Duals
Casablanca’s hippodrome is organizing a new type of horse racing:
duals. During a dual, only two horses will participate in the race. In
order for the race to be interesting, it is necessary to try to select
two horses with similar strength.
Write a program which, using a given number of strengths, identifies the
two closest strengths and shows their difference with an integer (≥ 0).
## Input
Line 1: Number N of horses
The N following lines: the strength P[i] of each horse. P[i] is an integer.
##Output
The difference D between the two closest strengths. D is an integer greater than or equal to 0.
##Constraints
1 < N  < 100000
0 < P[i] ≤ 10000000