java - 多项计划

Question

这是我要解决的编程问题:2520 是可以除以从 1 到 10 的每个数字而没有余数的最小数字。

能被 1 到 20 的所有数字整除的最小正数是多少？

到目前为止，这是我的解决方案，但答案每次都是零，所以我认为我的代码有错误。任何帮助将不胜感激。

public static boolean isDiv(int num){
    boolean isDiv = false;

    for (int i = 1; i <= 20; i++){
        if (i == 20){

            isDiv = true;

        }
        if ((num % i) == 0){
            continue;

        }
        else  {
            break;
        }

    }


return isDiv;}

public static int smallMulti(int num){
    boolean div = isDiv(num);
    int answer = 0;

    for (int i = num; num < 2520; i--){

        if (div = true){
            answer = i;
        }
    }

return answer;}

Answer 1

您使整个问题过于复杂，并且存在多个逻辑错误。基本上你只需要 2 个循环。这是检查每个数字可见的第一个数字的代码，直到 Integer.MAX_VALUE。如果你想走得更高，你可以采用代码来处理 long。

public static int smallMulti(int num) {
    for (int i = 1; num <= Integer.MAX_VALUE; ++i) { // Check every int in the scope of the Integer
        for (int j = 2;j<=num;++j) {
            if(i % j != 0) {
                break; // If i % j is unequal to 0 then this number isn´t valid.
            }
            if(j == num) {
                return i; // If we reached j == num then everything was divisble yet so we can return i as the correct value;
            }
        }
    }
    return -1;
}

这是这个 main 的示例输出

public static void main(String[] args) {
    for(int i = 2; i <= 20; ++i)
        System.out.println("Smallest Value divisible by 1-"+ i + " = " + smallMulti(i));
}

输出

Smallest Value divisible by 1-2 = 2
Smallest Value divisible by 1-3 = 6
Smallest Value divisible by 1-4 = 12
Smallest Value divisible by 1-5 = 60
Smallest Value divisible by 1-6 = 60
Smallest Value divisible by 1-7 = 420
Smallest Value divisible by 1-8 = 840
Smallest Value divisible by 1-9 = 2520
Smallest Value divisible by 1-10 = 2520
Smallest Value divisible by 1-11 = 27720
Smallest Value divisible by 1-12 = 27720
Smallest Value divisible by 1-13 = 360360
Smallest Value divisible by 1-14 = 360360
Smallest Value divisible by 1-15 = 360360
Smallest Value divisible by 1-16 = 720720
Smallest Value divisible by 1-17 = 12252240
Smallest Value divisible by 1-18 = 12252240
Smallest Value divisible by 1-19 = 232792560
Smallest Value divisible by 1-20 = 232792560