Question

How to find the 100001 prime number in Swift

Answer 1

import Foundation

func isPrime(_ num: Int) -> Bool {
    if num < 2 { return false }
    if num == 2 { return true }  // 2 is prime

    let limit = Int(sqrt(Double(num)))
    if limit < 2 { return true } // No need to check further

    for i in 2...limit {
        if num % i == 0 {
            return false
        }
    }
    return true
}


func findNthPrime(target: Int) -> Int {
    var count = 0
    var number = 1

    while count < target {
        number += 1
        if isPrime(number) {
            count += 1
        }
    }

    return number
}


let target = 100_001
let result = findNthPrime(target: target)

print("The \(target)st prime number is: \(result)")



/*
run:

The 100001st prime number is: 1299721

*/

 

70+ SQL courses for beginners and professionals