1.3 KiB
1.3 KiB
| title | localeTitle |
|---|---|
| 10001st prime | 第10001个素数 |
问题7：10001个素数
方法：
- 素数是一个除以1和自身的数字。
- 我们可以发现一个数字是素数，如果它不能被小于其自身的其他素数整除。
解：
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 <= its 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];
}
- 运行代码