ianadiwibowo/central-park

package main

import (
    "math"
)

// Primality checks whether number is prime using trial division algorithm
func Primality(number int32) string {
    if number < 2 || hasSmallFactor(number) || hasBigFactor(number) {
        return "Not prime"
    }
    return "Prime"
}

func hasSmallFactor(number int32) bool {
    smallPrimes := []int32{2, 3, 5, 7}
    for _, n := range smallPrimes {
        if number > n && number%n == 0 {
            return true
        }
    }
    return false
}

func hasBigFactor(number int32) bool {
    limit := int32(math.Sqrt(float64(number)))
    var i int32
    for i = 11; i <= limit; i += 2 {
        if number%i == 0 {
            return true
        }
    }
    return false
}