How to remove repeated element in a slice? - go

Question

I have made a code to generate random numbers and delete the repeated ones like below:
package main
import (
"fmt"
"math/rand"
"time"
)
func main() {
list := [7]int{}
for i := 0; i < 7; i++ {
here:
rand.Seed(time.Now().UnixNano())
s := rand.Intn(16)
fmt.Println(s)
if s != list[0] && s != list[1] && s != list[2] && s != list[3] && s != list[4] && s != list[5] && s != list[6] {
list[i] = s
} else {
goto here
}
}
fmt.Println("list:", list)
}
I noticed that there were a lot repeated code like:
s!=list[0]&&list[1]
But when I write it to:
s!=list[0:6]
It is wrong, how can I do this properly?

Answer 1

Store it in map.
like that
rndmap := make(map[int]bool)
for len(rndmap) < YOUR_LEN {
rndmap[rand.Intn(YOUR_MAX_RAND)] = true
}
Result map will never store repeated indexes.
You can convert it into slice like this
rndslice := make([]int,0)
for i, _ := range rndmap {
rndslice = append(rndslice, i)
}

Answer 2

You can use the standard library to generate the random elements without any repetition in the first place.
package main
import (
"fmt"
"math/rand"
)
func main() {
fmt.Println(rand.Perm(16)[:7])
}

Answer 3

If you want a way to check a slice of ints for a value, try this function (play.golang.org):
func InSlice (arr []int, val int) (bool){
for _, v := range(arr) {
if v == val { return true; }
}
return false;
}
You can use this like below, but you won't be able to run it succesfully on play.golang.org because play.golang.org has a deterministic response to math/rand (In my case, it's 0), which will keep it from giving more than one answer, forcing this code into an infinite loop.
func main() {
list := [7]int{}
for i := 0; i < 7; i++ {
here:
rand.Seed(time.Now().UnixNano())
s := rand.Intn(16)
fmt.Println(s)
if !InSlice(list[:], s) {
list[i] = s
} else {
goto here
}
}

Answer 4

The following program will pick the array passed in the function findDuplicates() and returns repeated / duplicate values in another array as output. Also if there are no duplicates the function will return -1.
package main
import "fmt"
func findDuplicates(arr []int) []int {
foundMap := make(map[int]bool, 0)
respArray := []int{}
for i := 0; i < len(arr); i++ {
if foundMap[arr[i]] == true {
respArray = append(respArray, arr[i])
} else {
foundMap[arr[i]] = true
}
}
if len(respArray) == 0 {
respArray = append(respArray, -1)
}
return respArray
}
func main() {
fmt.Println(findDuplicates([]int{19, 22, 22, 100, 1, 1, 1, 22, 88}))
}
// Output [22 1 1 22]