CareerCup

Using sieve of erotospenes, complexity O(nloglogn):

package main

import (
	"fmt"
	"math"
	"math/rand"
)

func main() {
	primes := findPrimes(225, 350)
	r := rand.New(rand.NewSource(7))
	fmt.Printf("random %d", primes[r.Intn(len(primes))])
}

func initArray(max int) []int {
	toReturn := make([]int, max+1)
	for i := 0; i < max; i++ {
		toReturn[i] = i + 1
	}

	return toReturn
}

func findPrimes(min, max int) []int {
	input := initArray(max)
	sqrtN := int(math.Sqrt(float64(max)))
	for seed := 2; seed < sqrtN; seed++ {
		for i := seed; i < max; i++ {
			if input[i] != -1 && input[i]%seed == 0 {
				input[i] = -1
			}
		}
	}

	toReturn := make([]int, 0)
	for i := min - 1; i < max; i++ {
		if input[i] != -1 {
			toReturn = append(toReturn, input[i])
		}
	}

	return toReturn
}

private int randomPrime(int min, int max) {
		int random = (int) (Math.random() * max);
		if(random < min) {
			random = randomPrime(min, max);
		}
		if(!isPrime(random)) {
			random = randomPrime(min, max);
		}
		return random;
	}
	
	private boolean isPrime(int random) {
		boolean isPrime = !(random % 2 == 0);
		if(!isPrime) {
			return false;
		} else {
			for(int i = 3; i*i < random; i++) {
				if(random % i == 0) {
					return false;
				} else {
					isPrime = true;
				}
			}
		}
		return isPrime;
	}

public class RandomPrimeNumbers {

// generate randmon prime number betweeb min and max
public static void main(String args[]) {
int min = 1;
int max = 11;
List<Integer> list = new ArrayList<>();
for(int i =min; i<=max; i++) { // O(max)
if(i != 1 && isPrime(i)) {
System.out.println(i);
list.add(i);
}
}
Random r = new Random(System.nanoTime());
System.out.println("Randmon prime :"+ list.get(r.nextInt(list.size())));
}
private static boolean isPrime(int n) {
for(int i = 2; i*i<=n;i++){ // this O(sqrt(n)) time complexity
if(n%i == 0)
return false;
}
return true;
}
}

public class RandomPrimeNumbers {

	// generate randmon prime number betweeb min and max
	public static void main(String args[]) {
	int min = 1;
	int max = 11;
	List<Integer> list = new ArrayList<>();
	for(int i =min; i<=max; i++) { // O(max)
		if(i != 1 && isPrime(i)) {
			System.out.println(i);
			list.add(i);
		}
	}
	Random r = new Random(System.nanoTime());
	System.out.println("Randmon prime :"+ list.get(r.nextInt(list.size())));
	}
	private static boolean isPrime(int n) {
		for(int i = 2; i*i<=n;i++){ // this O(sqrt(n)) time complexity
			if(n%i == 0)
				return false;
		}
		return true;
	}
}

public class RandomPrimeNumbers {

	// generate randmon prime number betweeb min and max
	public static void main(String args[]) {
	int min = 1;
	int max = 11;
	List<Integer> list = new ArrayList<>();
	for(int i =min; i<=max; i++) { // O(max)
		if(i != 1 && isPrime(i)) {
			System.out.println(i);
			list.add(i);
		}
	}
	Random r = new Random(System.nanoTime());
	System.out.println("Randmon prime :"+ list.get(r.nextInt(list.size())));
	}
	private static boolean isPrime(int n) {
		for(int i = 2; i*i<=n;i++){ // this O(sqrt(n)) time complexity
			if(n%i == 0)
				return false;
		}
		return true;
	}
}

here is some code with python

# write a function that randomly return a random prime
# number in range [min, max)
# public int getRandom (int min, int max){}
# April 2017
import random


def getRandom(min, max):
    if  min > 1:
        rangeRover = random.randint(min, max)
        for i in range(min,max):
            if rangeRover % i == 0:
                return False
            else:
                return rangeRover
    else:
        return False

print('my random numbers based on given range', getRandom(12,407))