如何找到0-100之间的素数? [英] How to find prime numbers between 0 - 100?

问题描述

在 Javascript 中，我如何找到 0 - 100 之间的质数?我已经考虑过了，我不知道如何找到它们.我想过做 x % x 但我发现了明显的问题.这是我到目前为止:但不幸的是，这是有史以来最糟糕的代码.

In Javascript how would i find prime numbers between 0 - 100? i have thought about it, and i am not sure how to find them. i thought about doing x % x but i found the obvious problem with that. this is what i have so far: but unfortunately it is the worst code ever.

var prime = function (){
var num;
for (num = 0; num < 101; num++){
    if (num % 2 === 0){
        break;
    }
    else if (num % 3 === 0){
        break;
    }
    else if (num % 4=== 0){
        break;
    }
    else if (num % 5 === 0){
        break;
    }
    else if (num % 6 === 0){
        break;
    }
    else if (num % 7 === 0){
        break;
    }
    else if (num % 8 === 0){
        break;
    }
    else if (num % 9 === 0){
        break;
    }
    else if (num % 10 === 0){
        break;
    }
    else if (num % 11 === 0){
        break;
    }
    else if (num % 12 === 0){
        break;
    }
    else {
        return num;
    }
}
};
console.log(prime());

推荐答案

这是我解决的方法.把它从 Java 改写成 JavaScript，所以如果有语法错误，请见谅.

Here's how I solved it. Rewrote it from Java to JavaScript, so excuse me if there's a syntax error.

function isPrime (n)
{
    if (n < 2) return false;

    /**
     * An integer is prime if it is not divisible by any prime less than or equal to its square root
     **/

    var q = Math.floor(Math.sqrt(n));

    for (var i = 2; i <= q; i++)
    {
        if (n % i == 0)
        {
            return false;
        }
    }

    return true;
}

一个数，n，如果它不能被除 1 和它本身以外的任何其他数整除，则它是素数.此外，检查数字 [2, sqrt(n)] 就足够了.

A number, n, is a prime if it isn't divisible by any other number other than by 1 and itself. Also, it's sufficient to check the numbers [2, sqrt(n)].

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