package main
import (
"fmt"
"math"
)
func isPrime(n int) bool {
if n < 2 {
return false
}
if n % 2 == 0 {
return n == 2
}
limit := int(math.Sqrt(float64(n)))
for i := 3; i <= limit; i += 2 {
if n % i == 0 {
return false
}
}
return true
}
func hasUniqueDigits(n int) bool {
var seen [10]bool
for n > 0 {
d := n % 10
if seen[d] {
return false
}
seen[d] = true
n /= 10
}
return true
}
func main() {
for num := 1000; num <= 9999; num++ {
if isPrime(num) && hasUniqueDigits(num) {
fmt.Printf("First 4-digit prime with all unique digits: %d\n", num)
return
}
}
fmt.Println("No such number found.")
}
/*
run:
First 4-digit prime with all unique digits: 1039
*/
