freeCodeCamp/guide/russian/certifications/coding-interview-prep/project-euler/problem-7-10001st-prime/index.md

title, localeTitle

title	localeTitle
10001st prime	10001st prime

Задача 7: 10001st prime

Метод:

• Простое число - это число, которое делится на 1 и само.
• Мы можем найти, что число является простым, если оно не делится на другие простые числа, меньшие самого себя.

Решение:

function nthPrime(n) { 
 
  //Primes array which will store all the prime numbers 
  const primes = [2]; 
 
  //Num is the number we want to check 
  let num = 3, isPrime = true; 
 
  //Looping until primes array is equal to n 
  while (primes.length < n){ 
 
    //All the primes numbers of a number is always <= it's square root 
    let max = Math.ceil(Math.sqrt(num)); 
 
    for (let i = 0; primes[i] <= max; i++){ 
      if (num % primes[i] == 0) { 
 
        //Looping till we find the prime 
        isPrime = false; 
        break; 
      } 
    } 
 
    //if Prime found, push it to the array 
    if (isPrime) primes.push(num); 
    isPrime = true; 
 
    //An optimization technique, since we know of all even numbers only 2 is a prime number, we can skip the rest 
    num+=2; 
  } 
 
  //Returning the last number 
  return primes[primes.length-1]; 
 
 } 

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